Gentlemen:
As far as Loco electrical contact problems, as a DCC decoder installer running my own business, I've encountered this on many engines! Mostly Bachmann Steam (4-8-2's, K4-4-6-2's), Athearn-Genesis Diesels, and even some of the older Atlas-Kato, and Stewart diesels(both made by Kato, or Bowser)!
The for the Bachmann 4-8-2 Steam, is to remove the wipers, that curve down toward the rail, and ad spring loaded "pin" wipers on the bottom axle cover, that line up 90 degrees directly with the backs of the wheel flanges!
To do this, I used 3/32" brass tubing, no longer than the width of the cover plate, and 1/16" solid brass rod 1/2 the lenght of the tubung, and Kadee knuckle springs! Round one end of the rod in your Dremel tool, and de-burr the other end. Plug the back end of the tubes, and super glue it to the cover plate. I solder a short piece of 30 ga. bare wire to the contact plate on the upper side, then solder it to the tube on the bottom. (If I could figure out how to attach a photo from my files here, I would?). Load the springs & pins, in the tubes, and fasten the bottom cover back down with the screws!
As far as the Athearn, Atlas, Stewart-Kato diesels, most of the time, the problem is with those "worthless" plastic caps, that hold the wires to the truck contacts! Whenever I install a decoder in one of these diesels(sound, or silent running), I remove the trucks, disassemble them, and solder new 26, or 28Ga. stranded wires to the contact plates, and re-install the assembled truck to the frame.
I never re-use those plastic caps---Throw them away! Instead, I use a good grade of black heat shrink tubing, enough to cover the wire end, where I solder it to the contact! I do the same thing where I solder it to the decoder contact tab, or wires, I us heat shrink tubing, nothing else.
Even my own Stewart-Kato "F-units" (all 23, or 25 of them?), I disassembled the trucks, throw out those wires with the "clips" crimped on the ends, that are fastened to the truck contact & DC lighting board. They get lose after use, and will cause your engine to stall, or the sound to cut in & out over uneven track, turnout frogs, & crossings!
Those wires I mentioned are too short anyway, to reach the tabs on most PC board type decoders (i.e. Sountraxx AT-1000, BW-1000, NCE-DASR, or other decoder makes), som take the time to run new ones, when you install your decoder! The time it takes, is worth the trouble it saves! You'll see a big difference in electrical performance!
Joe Bliss, Allegheny Model RR Services
