Vintage Lionel 2020 worm gear problem

[atgiuffre]

I have a vintage lionel 2020 with a worm gear problem. Locomotive runs 100% in reverse but needs full throttle to run forward. Need verification, do I have to change drive gear.

 

[ekuth]

Welcome, and I wish I knew for certain.

I would hazard a guess that the problem either lies there, or with the brushes; have you cleaned the motor?

I had an American Flyer S-Guage that had a similar problem and the motor brushes turned out to be the culprit. A good cleaning took care of it.