Not enough information
The motor could eventually fail but we can't tell
Have you checked / changed the battery?
Are AAs being used in the battery pack and not a 9volt, also not rechargeables?
Can you hand wind it?
Has anything recently happened to it? Jams, has it slowed and stopped etc
Has any programming been done?
Ultimately if the motor is suspected strip it and connect power to just the motor
Or the belt has come off/snapped/got stretched somehow.