stuck might mean the belt has slipped.
maybe it slipped off.. make it broke in half.. maybe the 'out' part of the belt is resting on the 'out' part of the gear, and together the resistance is high enough to cause a stop.
this could be good for you, because if the assembly rotates some more.. the belt might fall completely off of the gear.
if the belt and gears are okay, then maybe the motor is weak or frozen/stuck.
and if the belt is good and the motor is good, maybe the controller for the motor is bad.
the controller might not be sending any electricity to the motor.. or the electricity that is being sent is not enough to turn the motor.
maybe the motor used to work at the voltage given by the controller, but has now become stubborn with age and wont spin with the same amount of electricity.
it would be embarassing to take the motor out and give it some voltage that is higher than what the controller gives, and see the motor spin fine.
it would also be embarassing to read the voltage from the controller while it is broken and try to use that amount of voltage to turn the motor.
maybe connecting a diagnostic tool onto the motor is enough to alter the atoms inside the magnet and create functionality again.
if the atoms did move, there is a right way to put them back.. because if you move them the wrong way, the motor might not work at all.. or it could develop another problem in the future.
i would think, if the atoms did move.. there wasnt anything there to prevent them from moving. and that is the key, if you put 'em back they might simply move again.. and maybe they move faster this time around.
i would say it would be worth it to open it up and have a look at the belt and see if the motor is jammed.
but i have had springs shoot out at me in the past and couldnt figure out how the spring went back to put it all back together.