[codefox1]

Had a few of these pass through my hands, and once determined that batteries were not an option, ripped out al the associated switches and whatever and made the set work on AC. Of course that means making the set work on higher mains voltage today, expecially if doing away with the "117" type rectifier. It is also likely that the prior repairs have now themselves expired, and the capacitors at very least need to be replaced once again. Whatever, make sure by incremental advances in your variac that filament string is correct.