Good luck. Let me know how it turns out.
If Athearn doesn't fix this issue then they will have some of the same problems when they come out with the Tsunami decoders.
Interesting I'll have to rip mine back apart and take a look. I had a similar issue with the MRC sound decoder in the Genesis F unit and the fix was to lower the volume to #1 oe #2 I don't recall I'll have to check my notes. The default volume is 3 and sounds ok when it does work but even ideling it would cut out. I was told by a tech at my LHS to try this as well as clean in the side frames witha broken off square tooth pick to remove all the gunk in the holes. So far knock on wood I haven't had a problem yet! not to say that I don't expect to have one again thats how much confidence I have in the Genesis and the MRC decoder right now. I will say your fix sounds a lot more plauseable, anything is possible do to the poor quality control they have. Two of my three genesis locootive were wired backwards right from the factory.
I have been struggling with several Genesis F-Units for some time now and was determined to find a solution to thier erratic performance. I have a CB&Q ABBA set of F-3s and a Rock Island F2, all delivered with the substandard MRC sound decoders. All of these units exhibited the same issue. They would stop and "reboot" every few feet as they traveled around the railroad. I couldn't tell if this was do to an intermittent short, a problem with power pickup, or an issue with the decoder.I started my debugging with the RI F2 since that was the worst offender. I first replaced the MRC decoder with a Soundtraxx LC decoder. While this gave me much better sound and motor control it did NOT solve the "reboot" issue. I next did some testing to find out if there was a problem with the motor. It bench tested just fine. Further testing confirmed that the problem is with power pickup in the trucks.My next approach was to solder the leads to the truck sideframes instead of relying on the plastic clips. This did NOT help. A closer inspection of the trucks finally revealed the real problem, and led me to the fix.The wheelsets have a split axle with a plastic gear in the middle. The axle ends extend into a metal bearing plate in the sideframes. This bearing plate should transfer both the electrical current and weight of the locomotive between the wheels and the trucks. The wheelsets fit into a gear tower and are held in place with a plastic plate that snaps onto the bottom of the truck. The two plastic sides of the gear tower have slots for the axles. The problem is that the slots are NOT DEEP ENOUGH. The plastic part of the axles rubs on the top of the plastic gear tower slots, causing the axles ends to "float" in the bearing plates resulting in intermittent electrical contact.The solution: Remove the sideframes and wheelsets. Take a small round file and file the axle slots in the gear tower to make them deeper. (You might want to completely disassemble the trucks to do this. I didn't bother since a few plastic filings shouldn't be too harmful.) Once this was done and the trucks were reassembled the problem was GONE! This fixed all my Genesis F-units. Yes I still have the other issues with the MRC decoders, primarily poor slow speed control, but the electrical issues are solved.