Jure,
Could you remove the knob and make sure that the pot is secure? If the pot is loose, I think there's a chance that it will shift as you tighten the collet knob. If the pot shifts, perhaps it places too much strain on a connection or causes a short. If the knob doesn't point to where you expect (min and max positions) after tightening the knob, I'd bet the pot is moving. This might also explain why you can't seem to get the knob tight enough.
By the way, you would be able to test SoM's theory while the knob is off as well.
If you find that the pot is loose, place it in the proper position before securing it, and of course, make sure that you don't over-tighten.
Thanks,
- nate.
(Message edited by cntrabssn on November 11, 2004)