Lionel Gang Car Won't Reverse

Since you have eliminated the missing top bearing ball as a possibility, I would check to see whether the wheels are rubbing against the frame in one direction.
This is a common problem.

The absolute best (and most involved) repair would be to replace the wheel bearings.

IMHO, the next best would be to remove the wheel on the offending side, and place one or two 671M-23 washers on the axle.
Some folks have reported that slipping a e-ring behind the wheel works too. I haven't tried this particular fix.

 

 

Well thank you, sir.  I will check that out.

I will have to try one of these fixes myself.  I have 3 of these gang car on the shelf and they all have had this problem.  I did get some improvement in the past by simply replacing the brushes. 

If that fix doesn't work, you may have a armature or field going bad.

 

  If all bearings are good, one other item that may be bad is the worm wheel. If it is worn, you will get poor performance. If the car runs good in one direction, the armature is definitely good. Field windings are pretty robust, and the armature would burn before a field winding. Check for a bad connection to the field windings, and pull the armature out to inspect the worm wheel.

 

Larry

Thank you, all.  Quite a lot of potential problem areas for what looks like a pretty simple item.

 

I believe my problem may be in the bushings:  With power on, I pushed the wheel inward toward the frame, and the car took right off.

I just had this problem and something I did really worked well. My gang. At would stop one way when I hit the bumper. The bumper was moving the electrical contact too far. So what I did was cut a small piece of double sided mounting tape (Scott's extra sticky) to the inside of the bumper. This extra thickness keeps the bumper from pushing it too far and it now runs like a top. An odd solve but I thought I would share what worked for me for this common one way gang car problem.