Well, after examining the contact plate and the wiring from the windings for a short as CWburfle recommended, I found the unit would run fine (in both directions) when the plastic shell was off, but when I placed the shell back on, the one direction problem reoccured. What I found was that the base of the metal lamp holder in the foam holder was being pushed down onto one of the soldered contact points on the contact plate. Once I placed a piece of electrical tape over the base of the lamp holder, I found the problem solved.
One more question. I see where others have had problems with the bulb melting the plastic shell. Is the foam supposed to cover the bulb or just the metal holder in order to prevent the heat? Is it possible to change to a lower heat LED light bulb in place of the original unit? I’m just interested in preventing any future melting.
Thanks