I took measurements with the original components for 6V6 dissipation.
This is what I got:
Cathode Resistor: 251.8 ohms (almost half the value that the schematic says).
Voltage drop: 20.3V (within specs).
Current would be around 80.6mA.
Plate Voltage: 248.1V (really low).
Tube Dissipation: 20 watts aprox.
This makes me wonder, how can I get almost the correct BIAS voltage with cathode resistor value drifted almost to half the value. I need to increase plate voltage to get the correct tube dissipation.
Probably what the amp needs is a recap job.