If it's moving normally but no sound, if you are lucky a DAT (same as DDS) cleaning tape might help. Supposedly they cause extra wear to the head, and often don't clean everything very well, but if you aren't into opening the deck and doing a manual cleaning with the right swabs (Chemtronics chamois tips), it might work.
Playing just a portion of a bad tape can clog a DAT head. At this time, many tapes are deteriorating and do this.