Combines F2 Sep Clutch

You probably have a build up of dust behind the clutch disc. I had this happen last year. I kept backing the clutch adjust ring off but still had the problem. Once I got it apart I found dust packed so hard I thought it was part of the disc lining.

yes, build up, OR the linkage has worn and you are trying to have the pivot rod "climb" out of the groove it has created.