Your cart is empty
Browse spare parts →
If your Bosch angle grinder is not working, don't assume that the whole tool needs replacing. A grinder that won't start, keeps cutting out, has lost power or makes unusual noises can often be suffering from a fault with a specific component.
Bosch produces a wide range of corded and cordless angle grinders, including models from the GWS, PWS and Professional ranges. The exact fault and replacement parts available will depend on your particular model.
In this guide, we'll look at the most common reasons why a Bosch angle grinder is not working, what you can check and which Bosch spare parts may be needed.
If you're looking for replacement components, you can browse our Bosch angle grinder parts and spares.
There are several reasons why a Bosch angle grinder might stop working.
Common problems include:
Bosch angle grinder won't start
Bosch grinder keeps cutting out
Bosch angle grinder has lost power
Grinder is sparking excessively
Grinder is making a grinding or rattling noise
Angle grinder spindle isn't turning
Grinder is overheating
Disc isn't spinning correctly
Cordless grinder won't work
Grinder switch isn't working
Before ordering replacement parts, it's important to establish exactly what your grinder is doing.
If your Bosch angle grinder won't start at all, begin with the simplest checks.
For a corded Bosch angle grinder, check that:
The plug is connected correctly
The socket is working
The power cable isn't damaged
Any extension lead is working correctly
Never use a grinder with a damaged mains cable.
For a cordless Bosch grinder, make sure the battery is charged and properly installed. If possible, try a known-good compatible battery.
If the power supply is definitely working, the fault could be inside the grinder.
Possible causes include:
Faulty switch
Worn carbon brushes
Damaged armature
Internal wiring fault
Motor problem
Damaged electrical components
If your Bosch angle grinder keeps cutting out, it may be activating a protection system because the tool is being overloaded.
Grinding heavily or using the wrong disc can put excessive load on the motor.
Check that the disc is suitable for the grinder and the material you're working on.
Also inspect the ventilation openings and make sure they aren't blocked with dust or debris.
If the grinder continues to cut out when running without a significant load, there could be an electrical or mechanical fault.
On some cordless models, the battery or electronic protection system may also cause the grinder to stop.
A noticeable loss of power can have several causes.
For a cordless grinder, start by checking the battery.
For a corded model, check the mains supply and cable.
If the power supply is good, worn carbon brushes or a damaged armature can affect motor performance.
A mechanical problem can also make the grinder appear underpowered. For example, damaged bearings or gears can increase resistance inside the tool.
If your Bosch grinder has gradually become weaker, inspect the consumable and internal components before assuming the motor needs replacing.
A small amount of sparking from a brushed motor can occur during normal operation.
However, excessive sparking shouldn't be ignored.
Potential causes include:
Worn carbon brushes
Damaged armature
Dirty or damaged commutator
Incorrectly fitted brushes
Internal motor problems
If the grinder is producing large amounts of sparks, smells of burning or is behaving differently from normal, stop using it and investigate the fault.
Carbon brushes gradually wear as the grinder is used.
When they become excessively worn, they can cause:
Intermittent operation
Loss of power
Excessive sparking
Difficulty starting
The grinder stopping during use
If your Bosch grinder is showing these symptoms, checking the carbon brushes is a sensible first step.
Different Bosch grinders use different brush types, so identify your exact model before ordering replacements.
If your Bosch angle grinder is making a grinding noise, there could be a problem with the mechanical components.
Possible causes include:
Worn bearings
Damaged gears
Damaged spindle
Loose internal components
Gear housing damage
Armature problems
A sudden change in the sound of a grinder can be a useful warning that something inside the machine is beginning to fail.
Don't continue using the grinder if you suspect serious internal damage.
If the motor appears to run but the spindle isn't turning correctly, there may be a problem with the gearbox or drive components.
Check the spindle and disc area for anything that could be obstructing movement.
If there is no obvious obstruction, the problem could involve:
Gears
Spindle components
Bearings
Gear housing
Internal drive components
A replacement gear or spindle component may be available depending on the Bosch model.
It's normal for an angle grinder to become warm during use, particularly when working under heavy load.
Excessive heat, however, can indicate a problem.
Potential causes include:
Heavy continuous use
Blocked ventilation
Excessive load
Blunt or unsuitable accessories
Worn bearings
Motor problems
Electrical faults
Allow the grinder to cool before inspecting it.
If it repeatedly overheats during normal use, investigate the cause rather than continuing to operate it.
The switch is a commonly used component that can eventually wear out.
A faulty switch may cause the grinder to:
Not start
Stop unexpectedly
Operate intermittently
Require excessive movement to start
Become difficult to switch on or off
If the switch feels loose, stiff or different from normal, it may need replacing.
Bosch uses different switches across its angle grinder range, so always match the replacement to your exact model.
On corded Bosch grinders, the power cable is another component worth checking.
A damaged cable can cause intermittent operation or prevent the grinder from working completely.
Look for:
Cuts
Splits
Crushing
Exposed wires
Damage around the plug
Damage where the cable enters the grinder
Never continue using a power tool with a damaged cable.
Replacement cables are available for some Bosch angle grinder models.
If you have a cordless Bosch angle grinder, the battery should be one of the first things you check.
Make sure:
The battery is fully charged.
The battery is correctly fitted.
The battery contacts are clean.
The battery is compatible with the grinder.
The grinder works with another known-good battery, if available.
If another battery works correctly, the original battery may be responsible.
If neither battery works, the fault is more likely to be within the grinder itself.
The armature is a major component of the grinder's motor.
A damaged armature can cause symptoms such as:
Excessive sparking
Loss of power
Unusual motor noise
Intermittent operation
The grinder failing to start
Burning smells
Replacing an armature can sometimes be a more economical repair than replacing the complete grinder.
However, armature replacement involves dismantling the tool, so make sure the correct part is identified before ordering.
Bearings allow the motor and drive components to rotate smoothly.
When a bearing becomes worn, you may notice:
Increased noise
Excessive vibration
Grinding sounds
Movement in the spindle
Reduced performance
If your grinder has become progressively noisier or more vibrational, bearings are worth checking.
The exact bearing specification varies between Bosch models.
The gearbox transfers power from the motor to the spindle.
Damaged or worn gears can result in:
Grinding noises
Rattling
Reduced power
Excessive vibration
Spindle problems
The grinder failing to drive the disc
If the grinder has been heavily used or has suffered an impact, inspect the gearbox and gears for damage.
If the grinder starts but the disc isn't rotating correctly, stop using it and investigate the cause.
Possible causes include:
Gear damage
Spindle problems
A mechanical obstruction
Damaged bearings
Motor or armature problems
Don't attempt to hold or stop the disc while the grinder is running.
Always disconnect the power source or remove the battery before inspecting the disc and spindle area.
Depending on your model, a range of Bosch angle grinder spare parts may be available.
These can include:
Carbon brushes
Armatures
Bearings
Gears
Spindles
Switches
Power cables
Gear housings
Covers
Springs
Washers
Retaining rings
Brush holders
Internal electrical components
Guards
Side handles
Other small components
You can browse our Bosch angle grinder spare parts to find parts for different Bosch models.
When looking for a replacement component, always search using your exact Bosch model number.
Popular Bosch angle grinder models include:
The GWS 7-115 is a corded Professional angle grinder. If you're looking for replacement parts, make sure you identify the exact variant before ordering.
The Bosch GWS 6-115 is a popular corded angle grinder. Different versions and specifications can use different components.
The GWS 850 range includes several Bosch angle grinder variants.
The GWS 9-115 is another popular Bosch grinder, with individual replacement components available depending on the exact version.
This is one of the most important steps when repairing your Bosch grinder.
Don't simply search for “Bosch angle grinder switch” or “Bosch angle grinder carbon brushes”.
Bosch uses different components across different models.
Instead, find the model number and, where applicable, the machine's type number.
You can then search for:
Bosch [model number] parts
For example:
Bosch GWS 7-115 parts
Bosch GWS 6-115 parts
Bosch GWS 850 C parts
Bosch GWS 9-115 parts
Once you've found the correct model, use the exploded parts diagram to identify the component and its part number.
| Problem | Possible cause | Parts to check |
|---|---|---|
| Won't start | Switch, brushes, armature or wiring | Switch, carbon brushes, armature |
| Keeps cutting out | Overload, battery or electrical fault | Battery, switch, motor components |
| Excessive sparking | Worn brushes or armature | Carbon brushes, armature |
| Grinding noise | Bearing or gear damage | Bearings, gears |
| Excessive vibration | Bearings, spindle or gears | Bearings, spindle, gears |
| Loss of power | Brushes, armature or mechanical fault | Brushes, armature, bearings |
| Spindle not turning | Gearbox or drive fault | Gears, spindle, bearings |
| Overheating | Excessive load or internal fault | Bearings, motor components |
| Intermittent operation | Switch, cable or brushes | Switch, cable, brushes |
Remember that these are possible causes rather than guaranteed diagnoses. The correct fault should be established before ordering a replacement component.
If your Bosch angle grinder has been reliable and the rest of the machine is in good condition, repairing it can make sense.
A grinder that won't work might only need a relatively small component such as a switch, carbon brushes or bearing.
Even more expensive components can sometimes be replaced individually, allowing you to repair the existing machine rather than replacing it completely.
Before buying a new grinder, it's worth checking whether the faulty component is available as a spare part and comparing the repair cost with the price of a replacement tool.
If your Bosch angle grinder is not working, go through these checks:
1. Check the power supply
Make sure the socket, cable or battery is working correctly.
2. Check the switch
Make sure the switch operates normally.
3. Check the battery
For cordless models, try a fully charged compatible battery.
4. Inspect the disc
Make sure the disc isn't damaged or causing an obstruction.
5. Check for overheating
Allow the grinder to cool if it has become excessively hot.
6. Listen for unusual noises
Grinding or rattling can indicate bearing or gear problems.
7. Check for excessive sparking
Worn brushes or an armature fault could be responsible.
8. Inspect for physical damage
Look for damage to the housing, spindle and other external components.
9. Identify the exact model
You'll need this information when ordering Bosch spare parts.
10. Check the parts diagram
Use the correct exploded diagram to identify the required component.
Check the power supply, battery, switch and carbon brushes first. If these are working correctly, the grinder may have an internal electrical or mechanical fault.
Overloading, overheating, battery problems or an electrical fault can cause a Bosch angle grinder to repeatedly cut out.
A small amount of sparking can be normal with brushed motors, but excessive sparking can indicate worn carbon brushes, a damaged armature or another motor problem.
Grinding noises can be caused by worn bearings, damaged gears, spindle problems or loose internal components.
Some Bosch angle grinders have replaceable carbon brushes. Make sure you identify the exact model before ordering replacement brushes.
Yes. Depending on the model and fault, components such as switches, carbon brushes, bearings, gears, armatures and cables can be available separately.
Identify the exact Bosch model and, where applicable, the type number. Then use the relevant parts diagram to find the correct replacement part number.
If your Bosch angle grinder is not working, don't immediately assume the complete tool needs replacing.
Start with the basics: check the battery or mains supply, inspect the switch and look for obvious blockages or damage. If the problem is more serious, components such as carbon brushes, bearings, gears, armatures and switches may be replaceable.
The most important thing when ordering Bosch angle grinder parts is identifying your exact model. Similar-looking Bosch grinders can use different components, so always check the relevant parts diagram and part number before ordering.
You can browse our full range of Bosch angle grinder parts and spares or explore our Bosch spare parts to find parts for your specific machine.
Always disconnect a corded grinder from the mains or remove the battery before inspecting or repairing it. If you're not confident carrying out an electrical or internal repair, have the tool inspected by a suitably qualified professional.
