I have a Lionel 6-18302 Great Northern EP-5 with Pulmor motors that has a problem with the driveshaft.

This is a brand new engine that I have had in the basement for a while. When I recently opened this engine the wheels on the train were frozen. After I manually moved the wheels for a while they became looser. I attempted to run the train, but it ran very slowly on the track.

I used some oil on the train which seemed to fix the problem. However, it was short-lived. The train ran perfectly for a bit but now now it does not seem to be running.

The wheels seem to slip on the driveshaft to the motor.

The wheels still spin as they should when manually moved. The horn works well.

I was wondering how to fix this problem? Thanks!