For those still interested in this saga. I received a call from the tech to tell me he was running the engine for 30 min. with no issues. The nest day I got another call and he informed me: " I was running it again with no issues and was about to wrap it up when it...stopped....then herky-jerky." He said he's sure it's a problem with the gearing in the front truck. The wheels would stop moving and the rear truck was trying to move the engine but of course couldn't. I'm so glad I sent it to MTH and that the symptoms showed up for the Technician. (Samuel). By the way, I've impressed with him and his customer support. Until the next time....keep those trains moving!