Intermittent low-level noise in intercom

[0TreeLemur]

I've been tracking down and eliminating noise in my intercom.  I found another source- the LED landing light switch.  When I switch it on with the engine off, I hear a low-volume noise.  The noise is a high frequency screechy noise.  Not constant frequency, just noisy and variable- kind of a continuous low-level screech.  When I put my hand on the landing light toggle switch and jiggle it a little, I can get that noise to stop.  The connections are tight.  The switch is tightly held to the panel.  Something wrong with the switch?  Anybody experience this?

[Vance Harral]

Sounds like the internal contacts of the switch are worn and/or dirty.  You might be able to clean them up by shooting contact cleaner into the internal guts of the switch, but it depends on how "sealed" the switch is.  If it's the old Klixon-style switch, I'd suggest carefully removing the plastic cover, spraying some contact cleaner into the switch, and working it back and forth a bunch of times.  May not resolve the problem, but it's a cheap and easy thing to try, and very unlikely to cause any additional problems.