I'm working on a Hammarlund SP-600 and need some advice. It receives on all
bands, but seems like it overloads after it has warmed up. After it's been
on about 15 minutes, the meter pegs and the RF gain control does not seem to
have any effect on signal strength. The signals become extremely loud and
rather distorted. All black beauties have been replaced as well as most of
the power supply caps.

Ideas about where to begin looking would be appreciated.

Thanks,
John