well there are a number of reasons
1 mechanical jamming. There can be 2 reasons for this A) the motor itself where the bearing fail and cause it to jam B) anything driven by the belt
2 electrical This motor has a start switch at the top end. if the contacts dont close properly when the motor stops the motor cant start
2 is my best guess. if it was 1 then there would be a possiblilty you would have burnt out your start winding. i would open the switch (carefully) and see if any of the contacts look a bit burnt. You cant get a new one so any repair would mean cleaning and carefully bending the contacts so they work
Dave