I restored a prewar 259. Kept all the wire but put shrink wrap on it to replace the junk insulation that was there. tore it down and and cleaned everything, armature face, brushes, fixed a bushing (anyone know what material Lionel used and if you can buy anything like it as I had to use a different material. It worksgreat but would like the look of the original stuff if possible). Two roller pickups on this engine have just one lead coming off of them. When running I can see light sparking coming off the rear roller. Once it has run a while it gets hot to the touch, but not the front one. I've checked clearance and it does not hit anything I can see and if I adjust it so it is not touching the third rail the train tends to cycle the e-unit easily to neutral on some spots on my track (same ones over and over-need to address that too) that it doesn't do with both pickups on the rail. It is not shorting the transformer and the engine runs fine, it is just that one roller. Anyone experience this before? Any ideas? Thanks.