I have two Spectrum 44 tonners with LokSound Micro 3.5 decoders. The installations are as nearly identical as they can be and each engine sounds and runs fine; they even share the same CV's, other than CV1! But one engine is very sensitive to dirty track while the other is almost impervious to such. I have checked electrical continuity--all wheels are fine; I've checked the movement of the trucks--each engine's trucks pivot and the wheels make good contact with the track. I have even checked to see if there is excess lubrication on the contact plates--there is not. The only variable is that the one 44 tonner (the one that rarely stalls) is the "old" one, pre-DCC ready version, converted from DC, while the other was a "DC ready" version and much newer and has run much less. The retainers for the trucks on the newer one are plastic rings while screws and a different piece are used on the older one. This does not seem to be a factor, however. It may be that the older engine is more "broken in." Is it possible that one of the decoders is more sensitive in regard to receiving a signal from the track than the other? How likely Is this? By the way, all my other engines run as well as the "good" 44 tonner and I do plan to "GLEAM" the trackage one weekend. The engine stalls on tangent track as well as on curves, usually in the same spots, even though the other 44 tonner rolls right on by these spots.
John C.
Your problem sounds like poor electrical pickup at the trucks on the one that stalls, or a loose wire on one of the trucks.
I'd look for the following problems:
If there's a lot of side play in the wheels on this model the pickup wipers may be losing contact with the sides of the wheels. I'd check the trucks very carefully under powerful magnification while moving the wheels from side to side and watching the pickup wipers.
And I'd check the solder joint where the wire is soldered to the pickup wipers. If it is just a press on fit, I'd solder it. I'd also tug slightly on the wire to make sure the conductors aren't broken off inside the insulation.