[Diverted]

Sounds to me like you have an issue somewhere before the 6A8G control grid. How are the voltages on the 6K7G RF amp?

This sounds very much like the classic bad antenna or RF coil on AM. SW...??? Did you replace caps (8 ), (20) & (21)? Also check resistor (9); if it fails, you lose AVC to the RF tube and the radio will exhibit the same symptoms as open antenna coils.

Found the issue. A stupid oversight on my part.

When I re-installed the tuning condenser, one of the unshielded wire leads leading to the fins ended up getting pushed up agains the side ofthe round access hole on the top of the RF chassis. So the wire was hitting the grounded RF chassis, grounding the fins on the back third of the tuning gang sections. It was just barely touching, but enough. Got home from work, noticed it, desoldered the lead and readjusted ... Bingo. Radio is playing strong and perfect across all bands. Thank god! It was a simple error.