How can I repair a Rotel RD-820 Cassette Deck?

The drive will not play or rewind or forward wind. The capstan spindle is not turning and the heads are not moving into position. There is a slight hum noise when the play button is pressed as though the motor was running or trying to run. I think the whole mechanism may have to be removed to enable it to be examined properly. Is it possible to get a service manual?

I have worked in a repair shop some years ago so I can get fairly technical and know how to use a meter.