[Elecraft] K3 phone plug

[W2BLC]

I had that problem early on and figured it was a film of some kind on 
the innards of the jack - had to wiggle the plug to get it to work. 
So........ I used some of that high dollar contact cleaner on the plug 
and then while it was still dripping wet, plugged it in and twisted it 
around for a few seconds. That fixed the problem. Your mileage may vary!

Bill W2BLC K-Line