I am currently working on two boxes: Hitachi 3D88 and CX-W700.
Both have the same problem with the left tape drive.
Both tape units are generally working fine.
However when the tape drive on the right side plays a cassette, the left tape drive makes a clicking noise once a second.
It sounds like it would like to auto-stop playing - even when it is already stopped.
It seems like the right tape drive is triggering the autostop on the left deck.
When I press the Pause-button on the (stopped) left tape the noise stops, but I guess the tape drive on the right side is intended to work without having the pause button pressed on the left tape drive?
Does anyone know this issue and a fix?
The original belts are still in use, but I do not think that this issue is related to problem of to low tension or similar.
P.S.: If there is anyone who has a service manual for the CX-700/750 - wink - wink ... I have the owners manual!