How to fix cassette deck?

The system comprises the cassette deck RS-EH600 twin deck. It has been cared for over the years but has decided not to work. Both decks do not play tape in either direction nor ffwd or rewind.The pinch rollers and spindles move. The capstans do not move, the system tries to move the tap then cuts off as though it cant move the capstans. When moved manually the capstans move in one direction freely and move on a ratchet type motion in the opposite way. Please help. Thankyou.