Hi Chris,?
This sounds precisely like the problem I had with my GM8. ?It's possible one of the bearing housings is misaligned with the main bore. ?When this is the case, as the clutch is tightened, the system is pulled further out of alignment creating binding. ?I outlined some procedures to check the alignment by using feeler gauges. ?
If you pull the worm, check for binding with and without the clutch tightened. ?This is a fairly definitive test. ?I'd be happy to answer questions as you look into it.
Best,?
Eric
Eric Chesak