Hi I have a champion 20v mill from chester machine tools. Its obsolete now I think. ANyway it started making that popping sound indicating a brush problem. It tripped my house ELCB twice! I took it apart and indeed found the brushes slightly worn. Problem is I'm finding it hard to find replacements. They measure 3.35mm x 9.9mm. It seesm the standard size is 10mm x 6mm.

I stripped down the motor and cleaned all the carbon off the commutator with 2000 grade emery. It was black with carbon. The brushes do seem to have a good bit of length left shortest is approx 10mm long. Maybe I don't even need to replace the brushes yet?

Anyway just wondering if anyone came across a similar issue and how you dealt with it. I guess I'll put it back together tomorrow and see it cleaning the commutator solves the problem. I guess in the long term I should probably look at replacing the motor with a belt driven 3 phase motor, but thats another days expense. Too much money spent on tools of late. Wait till the wife finds out!

Cheers
Dave.