Per the above, using contact cleaner, what's the best way to clean the motor?
Just give it a little squirt in the brush area. Spin the motor a few times and give it another little squirt from the other side. If you have compressed air available, a light blowing afterwards is helpful. Let everything dry completely before putting juice to it.
Washing away residual carbon dust and cleaning/de-oxidizing the commutator is what you are doing.
Toy train motors use bronze bushings but if you are cleaning a motor that uses ball bearings you should lube the bearings afterwards.
