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Look for shorted .047 cap in the boost to B+ circuit.
Clip screen resistor pin 4 and check for -45 volts on 12DQ6, pin 5. You can trouble shoot without cooking 12DQ6s with screen voltage disabled.
If still no answers, check for low resistance from damper cathode to ground. That points to shorted electrolytic or less likely, yoke.
Remember to re-solder the screen resistor once you find the trouble.
If no neg 45 volts, clean freq and hold controls, look for open lug ground near 6CG7, controls. Oscillator shut down could be a number of causes. Let's explore the other options first and let us know.
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