if it moves when the car is started in gear , then the cluch plate is possibly in the wrong way , or as u say the plate isnt releasing due to clutch cable length , had same issue coulple of weeks ago ,and it was cable length.
although we now know that the ratchet can be adjusted with a bar at the pivot pin , pressing the clutch pedle down ,apply pressure on the clutch arm in the direction of the bulk head ,slowly raising the pedle the rachet will click to dajust ,,
sorry if i am telling u what u may know but thats all i can think of