Hello, I am new here, I have a technical service of pro audio in Spain, and a client brought me to repair a sc5000m with the same symptoms that are described above, after reviewing many hours the device, I have found the fault and in my case it is not mechanical but electric, the engine module must reach 28vdc and in this unit only 19VDC arrived this makes the motor have less force and turn slower, the problem was in a DC/DC converter that increases the voltage of 19VDC of the power supply up to 28VDc of the motor, once repaired this simple failure the device works well 100% Greetings! Sorry for my english