These MP15ACs (I have 5 of them, non-sound) are about the pickiest about clean track and wheels. Just no room to put any weight in. The blackening agent on the wheels may also be causing part of the problems. I used a Trix wheel cleaner to help one run decent. Good luck.
Mike WSOR engineer | HO scale since 1988 | Visit our club www.WCGandyDancers.com
Did that decoder come with a "stay alive" capacitor? I know it's a snap in, but I'm not sure if there is one on board. They've been including a capacitor in their packaging of late, did it come with one?
I'm trying to model 1956, not live in it.
I think you can check for the accidental removal of one of the truck power feeds pretty easily without removing the shell.
First, check with a meter to see that you actually have power before and after the frog. Then run the engine slowly forward from the point end of the turnout toward the frog. Note which truck stops on the frog. Now do the same thing except turn the engine around such that the other end is running toward the frog. Note which truck is on the frog. If the same truck is on the frog, then your problem is in the power pickup from the other truck (the one that should be sitting on a powered section of the turnout).
I recently followed careful recommendations and retrofitted my early Athearn Genesis MP-15AC Switcher MRC decoder with the recommended Tsunami EMD non-turbo TSU AT1000 decoder. All work was meticulously done, but now (unlike the rest of my Atlas, BLI Paragon fleet), only this engine stalls at every switch/turnout. All my other engines glide flawlessly over the turnouts at low speed, and I am aware of the "DCC Compatible" "dead frog" issue, but this is the only engine that loses power at each turnout. Did I accidently "remove" some of the 8 wheels power pick up somehow? Thanks!
PS: I ordered the latest Athearn Genesis MP-15AC switcher with Tsunami Decoder already installed and hope this doesn't happen with the "out of the box" installation.