[Elecraft] unusual problem

[Lou Kolb]

Recently, I started noticing a strange sound from my K3-4290.  When keying 
the rig on CW I'll hear a crackling or almost a gurgling sound coming from 
the radio itself.  It's only happened 2 or at most 3 times but this morning 
I smelled something for the first time.  It started happening right after I 
upgraded the firmware although I doubt there's a connection.  I'm guessing a 
coil could be arcing, although as a person who is blind, I'm afraid I can't 
offer any visual data.  Any thoughts?  Lou WA3MIX