I wanted to post some info- it may help someone in the future, and save you a few weeks of head scratching...
I have a 2-8-0 MTH steamer from a rtr set. For some reason, it started throwing the rear tender wheels when going through my 0-42 curves & switches. After an extensive investigation, I discovered the tether cable had come out of the tender a bit too far. This was causing the tender & engine not to take curves, putting pressure on the rear axle throwing it off the rail.
Just a heads up in the even someone else has a tethered locomotive start acting goofy on curves.
I slipped the cable into the tender a little, and she is pulling the cars through the layout like a work horse again.
