120mm custom brushless dc motor winding stator and rotor assembly with rotor shaft

1 - Motor has been running then fails to start,what to do?
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.

2 - On initial installation, motor fails to start up,what to do?
Likely cause: Motor is incorrectly wired
What to do: Verify that the motor is wired correctly.

Likely cause: No output power from controller.
What to do: Measure voltage coming from the controller.

Likely cause: Motor is damaged and the armature is rubbing against the magnets.
What to do: Disassemble motor and see if the armature can be realigned by reassembly. Motor may have to be replaced.

3 - Motor takes too long to accelerate,what to do?
Likely cause: Motor controller not properly set.
What to do: Adjust the acceleration trim pot of the controller.

Likely cause: Brushes are worn.
What to do: Verify brush length.

Likely cause: Bearings may be defective.
What to do: Inspect bearings. Noisy or rough bearings should be replaced.

4 - Motor runs in the wrong direction,what to do?
Likely cause: Incorrect wiring
What to do: Interchange the two motor leads.

5 - Motor runs OK but has a clicking noise,what to do?
Likely cause: Suspect a burr on the commutator.
What to do: Remove burr from commutator using a commutator stone.