I have used the MTH motors for those, it's a bog-standard motor. Drop me a line if you need a motor, it's silly to buy a whole smoke unit for a $5 motor. For this unit, it could also be the smoke fan regulator components, there are three small parts that regulate the AC for the DC motor, those are also available.
FWIW, it is a big can motor that powers this one, it's the Pittman DC motor.