Volume Drop in '73ish V4B

[neddyboy]

Hi Liquids, thanks for the reply. Flyback diodes would be a first for me. Would those be D7-D10? All the amps I've worked on have been simple 2-tube PP Fender-ish designs -- this V4B is pretty intimidating! FYI definitely not plugged into the ext.speaker jack, and I swapped a set of KT66s in to rule out the KT88s as the problem. That's a drag to hear about the EH KT88s. Did the blown tube take out any amp components?