Gary,

FWIW, I found a PDF of the Service Manual for 765 and a Yahoo Group that had
some good threads on this very problem. Seems likely that my problem is a
failed RL201 relay on the Antenna Switch Unit. I was able to easily get the
Tuner Unit out (after finding those threads) and pull the Tuner Unit with
RL13 out of the loop and found that the relay RL201 which switches the tuner
out on Receive worked on one side and not the other.

So, hopefully replacing that relay will do the trick!

FYI

Mark