[Elecraft] New (to me) K2 needs help

[john]

I got a K2 in trade some weeks ago, and while it's in great shape,
its nowhere near as sensitive as my Drake TR7, for example. It seems
down on sensitivity on all bands. I have the radios on a common
antenna and can switch back and forth rapidly...and clearly there's an issue.

I very much want to keep this radio (I've wanted a K2 for a long time)
and would solicit inputs on how to best approach trouble shooting.

One other symptom is a ripple on received CW signals.

Thanks for any leads! I was disappointed to hear that this rig didnt
hear as well as existing rigs.  I don't think I have serious pilot error
(though I wont rule that out!)....

73
John K5MO