Sorry mate I don't know the brush sizes, I never needed to go that far.
Unfortunately to get to the brushes you still need to strip the motor which involves a bit of soldering and unsoldering wires (2 or 3) but looks easy from when I looked.
Cheers
Steve
Thanks, Steve. I think I may have a go at it anyway in a couple of weeks time when my mate gets back from holiday - he's more confident than I am at these things!
Cheers