The self-propelled unit has a specific gear set (part 203-3) and a motor & gear assembly (part 203-2). A grinding noise indicates gear damage or a failed bearing in that assembly.
- Inspect the gear set for stripped teeth.
- Check the motor & gear assembly for seized bearings.
- Verify the hexagon socket screws (part 203-6, 10 required) securing the unit are tight. Loose mounting can cause misalignment and grinding.
If the gears look intact, the issue might be in the wheel assembly hubs. The hubcap (part 36) or wheel assembly (part 37) could have debris jammed inside, causing the gear to grind against the housing.
Do not operate with a grinding noise. It will cause further damage to the gear set and motor assembly. The repair requires disassembly of the self-propelled unit.