I got my old Athearn BB HO cars and locos out of a 20 year storage and tried to clean them up. I wanted to setup a simple loop on my ping pong top for my nephew for Christnas. The Athearn loco wheels were oxidised and needed a good cleaning. I tried an old t-shirt soaked in TV tuner cleaner ontop of a section of track and aligator clip jumper wires for power, the results were minimal. Also I realised after doing the second loco that some of the wheels slipped. Upon taking them apart 80% of the drive gears that the two wheel halves slide into were cracked right down the middle. Well I don't know if it was age, they are over 20 years old, or the pressure of cleaning did the damage. I think they are just getting brittle from age. I will get some replacement gears at the hobby store. I ended up taking the wheel halves and chucking them in my Makita drill. Then I used mag aluminum wheel polish and an old sock and spun them in the drill while I polished. The drill does all the work and they come out better than new. They look like high end plated wheels.
Jerry