Oh, I see. I was assuming that you had one of the newer SW77s, with the
11 element telescopic antenna. If you have one of the older models,
with the 9 element antenna, then I can't hazard a guess about what the
problem might be. I've never used one of those units, but they
apparently did suffer from a range of problems that disappeared in the
later ones.

Maybe someone else has an older unit and can float a few hypotheses.
Good luck with it!

Best,

Steve