Discovered, by sheer chance, a problem with one of my Bachmann Spectrum2-8-0s tonight.
The other three all run with the tender connected (Which it has to be) but the tender wheels don't have to be in contact with the rails. Normally, the locos pick up through the driving wheels plus the tender wheels but the tender wheels aren't required for pick-up, they're a (smart) bonus.
However, the forth loco will not run unless the tender wheels are in contact with the rails. It's apparently either not picking up with the left hand drivers, or there's an incomplete circuit somewhere. I've removed the keeper plate holding the drivers and pick ups in place, and the two solder joints, that attach the red and white pick up wires, are good.
Anyone got any ideas?
-- Cheers Roger T.of the Great Eastern Railway