Connectivity

[Herc Driver]

I'd look at the metal electrical pick-up taps on the engines and clean them if needed. Seems to me that after a few months, those metal strips can be dirty enough to affect engine electrical conductivity. I have some 600 grit sand paper that I lightly rub over the metal strips to clean them up, but I don't know if that is the best thing I should use or not. A polishing cream would probably be a better choice I suppose.