[John Bartley]

Not a Zenith expert, but I have worked on one of these. I also had a problem with the FM, mine being a cut out and cut in problem. It turned out to be silver mica disease in the first FM IF. Unlike the same issue with AM, this SMD caused no thunder/crashing noises on FM (yours may be different).

I will try to attach a schematic (not sure it is the correct one, but it might help).

cheers

John

EDIT :: nope, I messed up the attachment ... gimme a minute ....

try this : http://oldradio.ca/radio/Info/Zenith_K73...ematic.gif