Originally Posted by
smitty55
Brushes will take on the curve of the commutator, you actually want as much surface contact as possible. I worked on many motors used on aircraft and often I would have to run the brushes in for a couple of days before the motor would meet specs of low enough current draw. The brushes and commutator look fine to me in that pic. I can't say for sure but many of the problems I see reported over time end up being issues with the foot pedals rather than the motor itself. There's lots on google about them and faulty switches.