Check your motor belt to make sure it is intact and moving properly. Another possible cause is that the brass screw (marked A in the picture) has worked itself out of the motor block and the tension of the belt pulls it away, preventing it from going in straight. Note that, depending on your type of motors, the brass bolt may have the larger or smaller pulley on it. The one that needs to be adjusted is the one with the brass color.
To fix this
-turn off power
- remove the belt
- unscrew the brass screw
- drive it back 4-5 turns, making sure that it is going in straight
- put back the belt
- turn on the power
You can check that the screw is at the correct height by looking at the drive wheel. If it is about a credit card height above the track when in manual mode, that is the correct position.
After replacing the screw in the proper position, check your motor belt for tightness. Loose belts are a common cause of bolts becoming un-threaded. If one of the motors is working, you can test by switching the two belts. If the belt is stretched or damaged, replacements can be purchased at: www.mcmaster.com. Use part number 3044K503 and select 5” outer diameter.
Also check the pulleys that the belt rides on for any damage or shininess. If they are damaged, you can get a belt and pulley set at www.quilttech.com.