Citizen 8200 series watch free spin unwinding

Hi there
New to this club, and to watch repairs, but I have a Citizen Diver Pro watch with the 8204 movement, and it doesnt want to keep its wind. I can manually or mechanically wind the watch okay, and it will work just fine if I leave it on the table, but when I put it on, quite soon afterwards it goes into a crazy unwind and makes quite a whirring noise for about 5 seconds as it completely unwinds.
Ive opened the watch and nothing appears broken. The click spring is in place, but doesnt seem very strong. The paul for the click spring engages on the lower wheel on the winding wheel with a one-way ratchet which appears to be working. I can only think of 3 reasons why it would go into a full unwind when moved - broken click spring; faulty ratchet wheel slipping perhaps; main spring problem?
I’m very new to this, and would appreciate any help anyone can offer. I know I can get a new 8205 movement, but not sure I want to deal with installing the hands and other than this problem, the watch keeps great time
Cheers