The Pergolux motor is not silent, so the motor making a noise during operation is completely normal. However, if the noise changes or does not sound right it is possible the washer on the backside of the motor arm is not in place.
You will need to re-install the washer onto the motor arm ensuring the screw and nuts are tight on the bracket and that the bracket is aligned correctly. Once this has been done, the motor should no longer make this noise