From the get-go, if I insert the headset jack all the way in, the headset does not work. If I leave around 3/16" showing, everthing works fine. Do I have a bad jack? Perhaps a stereo jack for a mono headset? My headsets are David Clarks passive units. (10-30's I believe...) When I say it doesn't work, I mean that I can't hear them and they can't hear me. Switching head sets doesn't help. Any thoughts?