I can't figure this one out. After applying power it just humms but doesn't move. There is no short but it seems the reverse unit cycles but the wheels don't turn. If you turn the wheels manually they are free just like a Lionel. The reverse unit, if that's what it is, is like something I have never seen. It's a metal box mounted to the rear of the motor with an impeller inside and a gear at the bottom front. See pictures. Any help would be appreciated. I have not been able to locate a spare impeller since this one has 3 blades broken off. It is a cast metal impeller. Maybe it's a whistle? Who knows? I had to pull a wheel to remove the 'reverse' unit. I'm pretty sure the person who worked on it before did the same thing and could not fix it, but put the wheel back on without aligning it with the front wheel so the side rods could be attached. This engine has no rods on the right side!!
All you American Flyer guys can chime in. The engine itself is in very nice condition, except it doesn't run! Also what is the red sliding piece for? Is that for locking into one direction? 
