I know when I clean a motor, I dismantle it completely as there isn’t a lot of parts to it but take note of the parts and I use isopropyl alcohol and an airbrush and spray everything till it comes clean. And when I put it all back together I put a drop of oil on the armature were it rides on the bearing blocks or where the metal contacts the plastic and using alligator clips and a transformer, hook the clips to the brush contacts and slowly add power and run it for a couple minutes at varied rpm and reverse same thing. As far as the loco goes I remove all the old lube and grease same way just both trucks and relive and drop of oil on shafts and such and rotate the wheels and gears to spread the lube and reassembly the loco and test it the same way as the motor. This has proven the best for me. Hope it helps you. And remember if the chassis does not freewheel well the motor is going to be working that much harder.