Unless the amps were modified there are not any regulators in the amps. A schematic wiring diagram can be found in the instruction manual.
Just a guess the power supply caps were replaced as well as any coupling capacitors.
I would probably pull all the tubes except the 5V4 full wave rectifier tube and bring the amps up slowly using the VARIAC. That will, should, reform the electrolytic caps in the power supply, if needed. If no smoke reinstall the tubes and bring the amps up on Line again with the VARIAC .
If in doubt though you might try sending a PM to @atmasphere.
Or if you are lucky he might read this thread and respond.
Just a guess the power supply caps were replaced as well as any coupling capacitors.
I would probably pull all the tubes except the 5V4 full wave rectifier tube and bring the amps up slowly using the VARIAC. That will, should, reform the electrolytic caps in the power supply, if needed. If no smoke reinstall the tubes and bring the amps up on Line again with the VARIAC .
If in doubt though you might try sending a PM to @atmasphere.
Or if you are lucky he might read this thread and respond.