American Flyer Sante Fe Engine frozen?

American Flyer engines have worm gears on their powered trucks and you can't turn them at all.  There is an reversing unit that sends power to the motors.  That is probably the buzz. 

There is a switch level on the bottom of the engine that keeps the revering unit from cycling.  Move it one was and try the engine. If it doesn't work move it the other way and give it power. The engine must be right side up for the reversing unit to function so on the tracks.

With as many years as this engine has not run.  There are many possibilities but what you wrote sounds like the reversing unit.

To add to Bill's post, if you do get the motors to run do yourself a favor and give it a complete lube job before you damage it. 45 years is a long time and whatever oil or grease it had back then has to be dried up and useless by now. This would include the axles, armature bearings and worm gears. You may need to remove any dried up grease on the worms to do it right. Use contact cleaner on the reverse unit to get it to rotate freely.

A popular culprit is going to be the reverse unit. The copper fingers will have lost some tension to keep contact with the drum, you will have oxidisation on the fingers and drum which will stop voltage/current flow. It will really need to be cleaned up carefully to make it function again.

As has already been mentioned the motors will need a good overhaul as well

Thanks to all. Amazingly when I took the cover off the wheel assembly, the gears were still wet with oil. It hadn’t dried out.

i will spend some time with the reversing unit and let you know what I find.