04-26-2016, 03:34 PM
Does the AVC voltage vary as you tune on and off a station? Check that on both the 12SA7 pin 8 and 12SK7 pin 4 tube, it should be a slightly negative value that goes more negative as a station is tuned in.
One of those two tubes could also be gassy and I would try the 12SK7 first.
Gregb
One of those two tubes could also be gassy and I would try the 12SK7 first.
Gregb