At first I just thought it was me and my hearing aids. That's always my first suspicion when I can't hear something that someone else can. In the cockpit, on the copilot side, I can hear the pilot fine, but anything coming from ATC, or ATIS is very muffled or nonexistent. This seemed to happen sort of suddenly one day, but then it fixed itself. Then it became more permanent. I tried the range of squelch/voume controls, but it didn't improve. Finally I tried switching headsets with Leslie, while leaving them plugged into their regular sockets, and she couldn't hear ATC either I tried pushing and pulling on the GMA340 volume/squelch know and it came off in my hand. I pushed it back on and it began working; sort of. Does this sound like a repairable issue? Should I just squirt some contact cleaner in there? I'd hate to replace the unit because of this, but if I do, what is recommended?