pull the side rods and make sure nothing is binding the wheels.
unhook the e unit and see if it runs then.
have you tried a different engine on your track to make sure the transformer of track isn't the problem? I've had track problems pop up out of now where, usually a switch or section of track shorting out. I set up my Uncle's train board this christmas, everything ran fine, set up the tree and then nothing. Traced it down to bad wires for the RC track.
