Motor has been running then fails to start

Likely cause: Fuse or circuit breaker is tripped.  

What to do: Replace the fuse or reset the breaker. 

Likely cause: Armature is shorted. Motor may make a humming noise and the circuit breaker or fuse will trip. 

What to do: Disassemble motor and inspect the armature for a burnt coil. Inspect the commutator for burnt bars. If this condition exists, the motor needs to be replaced. 

Likely cause: The brushes may be worn down too far and no longer make contact with the commutator. 

What to do: Check the brushes to make sure that they are still making contact with the commutator. Contact manufacturer for brushes. 

Likely cause: Controller may be defective. 

What to do: Verify voltage is coming out of the controller.