I had my MR2 up on blocks yesterday to run some cables. I noticed that there is some mild scoring (worst groove is maybe 0.5mm deep) on the motor commutator. The motor has a little over 10K EV miles on it now and while it wasn't new when I got it, the comm had no such wear on it at that time.
The motor is rear mounted (mid engine car) and is low enough that it probably does get some road dust during normal operation. There is a cowl around the brushes to keep the big junk from getting in there.
The motor is still functioning fine.
I've done precisely squat to the motor (other than paint it since it was a little bit crusty) since installing it in the car.
Anything to worry about? Suggested steps? (sorry, no pics)