I have a Ryobi RBC1020 electric brush cutter and grass trimmer. The motor has just started to excessively spark and rotation has virtually ceased. In taking it apart the only visual problem that I can see is that one of the carbon brushes is chipped on one edge and there is some loose carbon dust. Cleaned brushes and rotor with methylated spirit, dried and reassembled, but problem continuing.

Is the solution to replace the brushes or could there be other obvious problems?

Ian, April 2014

Sorry, the links didn't work:

Electric Motor Repair Brushes

Electric Motor Rebuilding Service

Paul Andre, April 2014

There are a few possibilities to your brush arcing problem. First, I would replace the brushes and see if that does the trick. A chip in the brushes can cause the brushes to lose their seated radius to the commutator and arcing can occur. If this is a permanent magnet motor, it is a DC motor and your DC rectifier or diodes may have gone bad and AC current from your homes' power supply may be leaking into the motor and will eventually cause the motor to completely burn up. Also very possible that your armature has shorted out and need to be replaced. There are a few other possibilities but the bottom line would be, replace the brushes and if that works, great, but if not, it is probably not worth going beyond that with this relatively inexpensive motor.

You can find the brushes and parts you need here: www.eurtonelectric.com

Paul Andre, April 2014