I have been following the procedure described in this video and it is a great aid to improving operation of my old Athearn BB diesels. If you have a drill press, invest a few bucks in a sponge (cut into smaller pieces) and some Mothers Mag & Aluminum polish. I also sand (clean) the brass wheel contact wipers with 400 grit garnet wet/dry paper. You will enjoy the results! https://youtu.be/TFxTNI-HILc
Cedarwoodron
I did that procedure to a Athearn BB GP7, and it helped a lot, especially for creeping over some of my old, reused hodge podge selection of #4 turnouts, that I used in some the industrial switching areas.
When I redo a BB loco now, I replace the wheel sets with the NS sets, from Athearn.
Mike.
My You Tube