Hi John. I'm glad you finally found a solution. Here is another issue that no one mentioned so far:
A few years ago I acquired several Athearn Genesis F3 and F7 units. As I converted them to DCC I programmed in momentum. I hard-wired the decoders so there was no issue with plugs or connectors. I also soldered the decoder leads directly to the trucks. They kept momentarily cutting out, and cycling through the startup sequence. Athearn sent replacement trucks, but they didn't help. The problem was with the truck design. The "wipers" that rest on the axles were not making good contact even after cleaning. I added tiny?phosphor bronze wires that contact the wheel treads, and that solved the problem. The?phosphor bronze wires were soldered to the brass truck parts meant to pick up current from the axles. This was tricky, and I used a resistance soldering unit and the resistance tweezers to hold the parts together while soldering.
Dale Muir
Geneva, IL
Dale Muir