[Elecraft] K2 audio problem

[Pawlak, Daniel L]

I'm having trouble figuring out what's wrong with my K2 (serial 3957). It's been a very long time since I turned it on and now the audio sounds horrible. It sounds like it's muffled or like I'm listening to the speaker at the end of a long tube. High frequencies seem to be diminished. I've started doing an alignment, but have not found anything wrong so far. Any ideas on how to fix this problem?
Thanks.
Dan Pawlak  KF4KKF
Manassas,VA