This Airzone Model 567 Chassis 527 was a customer repair job. The set was not operating and had a miniature 6V6 adapted to a 6 pin base in place of the 75 tube. The set had been worked on before possible in the '70s. I found a good 75 tube to remove the 6V6 and make the set look more original, even though it had shielding around it. The dial had 2 separate dial strings. I restrung one as the other one looked fine, changed the Caps, blew out the dust, checked all the voltages when I powered it up and NOTHING. As you can see in the lower middle shot of the chassis, I soldered 2 strands of copper wire as the riverts were a bit loose, thinking it was a bad shield earth, No. I was lucky to find a close schematic of an Airzone 520 (kindly shared online by "Restoring Vintage Radio"), which had the same valve layout 80, 42, 75, 6D6, 6A7. I compare the circuit and tried a resistor on the Cathode of the 75 that was not on my set but was on the 520 schematic and away she went. I had to try various size resistors untill I tested just the right cathode voltage. I also found a wire on the speaker terminal that was never soldered and causing an intermittent loss of the station. Customer kindly shared cabinet pictures. The output of the Rectifier tube was putting out 417vdc.