My Stewart/Kato F3 with LM3-S had been running fine for months, this week I did some detailing, removing and replacing the shell. Then I got an overheating alert and the unit shut down. Thought I'd jostled some wires so I tested it, looked for shorts, none apparent, put it back on the track and the LM started heating up with just a little running at low speed, and also standing still. Tried disconnecting the truck and motor wires and resoldering, same results. Any ideas? Thanks.