The bearing would be in the motor. While I'll admit it may be possible to replace the bearing depending on which one is giving you problems, I don't see it being an easy task. Unless you work on motors, you may not have the correct tools to make the motor's rotor line back up with the motor's stator to make it run. Also, to find out what bearing you would need you would either have to contact the motor's manufacturer and have them tell you what it is on their drawings or look on the bearing once you've pulled the ball bearing out of the motor. However you may not have a ball bearing in your motor, which would add to the difficulty in finding a replacement. I would just get a new motor.