Re: Identifying stepper motor in order to replace
There are no mechanical mating parts inside of a stepper motor. The coupling is all magnetic. They can ''grind'' away all day long and not be damaged. The noise is caused by the magnetic decoupling of the stator/rotor. It goes back to normal once power is removed.
Something else is the cause of your problem there. There is a very remote possibility that the press fit between the rotor and the shaft has come lose, but I have never seen this happen. If the stepper motor is connected to a gear box, then it is possible that the gearbox is damaged, but even this is not common. I'm not able to see exactly what the stepper is driving, but from your description I suspect it's just a pulley that drives the belt.
It is possible that the pulley is loose on the motor shaft.
Jim Dawson
Sandy, Oregon, USA