Over the years I have gathered 3 Rivarrosi O gauge diesel locomotives. All use the same motor - a "can" style motor on the middle of a shaft with a worm gear at each end (a bit like the old Tri-ang motor bogie).

1. Works well in both directions
2. Stays stalled, even on full power, until given a nudge in the right direction
3. Has never worked
   

Has anyone any thoughts on what is wrong with no 2?

Does anyone know of a source of replacements (other than another loco) for no 3?

John H.