Quote:
I'll try some switch contact cleaner if I can get the nozzle anywhere near an opening. Any other suggestions?

First, don't ever use cyanoacrylate near anything with electronic contacts. That stuff puts off nasty fumes and seeps into every nook and cranny. I wouldn't be surprised if it were the cause of your problem.

The knob board does not need to be glued down for any reason that I can think of, but if you must do it, use a very tiny dab of hotmelt glue, in a place where it can be easily plucked off if need be.

Anyway, you might be down to replacing the encoder if the contact cleaner doesn't work. The trick is that there's no way to get the encoder off of there easily without destroying it in the process. It's either destroy the encoder, or rip up traces on the display board trying to desolder it. And guess which one of those is an irreplaceable part?