Got this one working fine this evening. Had the typical full power tx with no modulation failure. AM Amp regulator TR-51 was shorted. That immediately fixed that issue. Then noticed weird RF output power levels and lack of stability. Found both VR10 & VR11 were open. Neither of them look diddled with, replaced and reset biasing on the IRF520's. Then found signal meter would not deflect at all on TX. VR8 was open! Then on RX just the little bit of receiver noise floor had the meter deflecting half scale. Pumping just 10uv or less into the RX would peg the S meter! moving VR1 had no effect. Found VR1 open! I guess what I can't quite believe is that all of this is coincidental or because someone diddled with all those VR's and burnt them. Didn't any look worn or messed with. After replacing them all and calibrating the meters with the service monitor, all is well! Just suspicious that some underlying event took all them out. Maybe a stray induced voltage from a nearby lightning hit?? If so I would expect finals gone. None of them are bad! Weird stuff. Anyone else have a similar type of parts failure combination on a non screwdrivered radio?? Just wondering!