[TenTec] Delta II/Argonaut II: RX audio issue

[Bill W1PA]

I was giving my Delta II a "check-out" this weekend, and noticed an issue with the RX audio.

The best way I can describe it is that it sounds like "de-sense" or strong adjacent signal overload...   the received signal sounds fine, and then suddenly goes garbled, almost like I hit "rev sideband". There is no change in s-meter or background noise levels. It comes and goes. When it happened the first few times, I searched for the strong station, but none is there (and then I verified there was none on another rig, switching it out A/B on the same station). It also seems to be somewhat sensitive to mechanical "shock" --  I can gently tap the rig, and sometimes get it to come back.

I am going to go through and exercise all the inter-board connectors (the Delta II has a lot of them), and put some deoxit in the pots. Any other simple things I should look at, or boards I should focus on in the audio or mixer chain?  I ran a bunch of QSO's in the contest this weekend, and a couple of longer QSO's, and there were no comments on transmit audio issues --   appears to be RX only.

Ideas?

Bill W1PA