Why do model trains stall?

Answer 1

Dirt might be around the motor and that could cause it to slow down and run harder. It would be a good idea to blow the dirt and dust away for the motor to make it run better or the motor could be weak.

It might be bad gap in track ,rust or dirt on the track : Check for bad gaps if OK wipe dirt off or use fine sand paper and take rust off (make sure when you are done to clean any dirt or grit off the track before running train on it ).

Hope this helps.