The older track power Bachmann locos had problems with the plunger style pickups. I didn't use them when introducing my BBT Drives. Bachmann has solved the problem by redesigning the wheel/axle hubs.
Well a new customer asked me if I could supply four of these. I said yes, but really don't want to send an item I know will fail in a short time.
I have been out of my shop for awhile and finally made it back in today. Got to playing around with this issue. The problem is that the current travels through the plunger, then through the spring and to the backing plate where the pickup wire is soldered.
I solve the issue on my BBT Drives by putting the spring and my plunger into a brass tube which bypasses the spring.
I took four of the stock Bachmann Plus plungers apart. Saved the good springs to re use. Took each of the backing plates and drilled 1/16" hole through the centers of each, actually enlarging the hole that was there.
Drilled a 1/16" hole in the center of the base of the brass plungers. Have two lengths of black #26 wire and two lengths of red #28 wire, which will be soldered to the plunger holes tomorrow. I will thread the springs over the wires, seat them on the back of the plungers. Insert the plungers and springs into each plastic housing, thread the wire through the holes in the base plates, insert the two screws into the base plate and attach the plate to the housing. Done. Remount into the Bachmann chassis and enjoy.
Barry - BBT