[codefox1]

I assume the rotary fins are shorting to the stationary fins, but it might be more serious than that. If it's really a goner, try to get a junker with a better one and proceed.

I would ordinarily blast out the old grease on the ball bearings with WD40, and then use a VTVM to detect shorts as I advance from full open to full closed position and bend the fins to eiminate the shorts. A digital meter will drive you crazy for this excercise. I just use a piece of paper to confirm my findings.

If the offending matter is dust and mouse s*it, blast it out with deoxit, or remove the whole contraption and boil it out (yes in an old pot) and let it dry for a day. Re lube the bearings with a little lithium grease. Remember that the mica trimmers must be disassembled, cleaned, and be put back in place. Of course this will require an alignment.