On small prewar electrics (248, 150 and 250 series is all I do is turn the loco upside down and power it up using alligator test cables. Then I hold piece of Scotch Bite on the wheels, cleans them up and there is basically no residue. On the smaller wheels I do what is described above taken them apart uninhabited it’s axle and holding then against a drill press mounted wire wheel.
I also would wipe them down with the 90% alcahole or any other type of solvent like lacquer thinner, acitone. Just have to make sure that the solvent you are using will not affect paint or plastics. Alway’s re-lube after a solvent is used.
Haven’t done wheels with traction tire, but If I did I would just work around them and do the others.
