Lionchief engines don't really have E-Units. Normally there'd be a switch under the cab to lock it in one direction if it was a conventional engine, but Lionchief engines don't have that feature since the remote choses what direction you go.
Check for anything that may have gotten wound around an axle. Hair, carpet fibers, etc. can get wound around the axles and bind the mechanism up, especially if its been running on a floor layout.
Another possibility, a friend of mine has a Lionchief 0-6-0 which I've had to disassemble a few times. The smoke unit piston is a very tight fit in the cylinder and can bind up and prevent the motor from turning the axles. My LC 0-6-0 hasn't had this issue yet, but I've fixed it on his several times.
