[exray]

I'm a fan of lots of knobs. I've got one set of headphones here that have, for whatever fault, different audio characteristics between the two phone elements. I can slowly swish through a signal with a 3-dialer and it seems like stereo as the audio goes from one ear to the other. Once you actually do that then the sweet spot sounds like stereo!

Your dead jack may be just poor connection. Many configurations killed the voltage to the unused stage(s) further downstream and generally a jack on the left would preceed a right-side jack so look further. Could be there's a poor connection on the left-side jack contacts or a problem in the next stage (like a bad xfmr?)

Another tidbit...It has been documented that 01As have a little burst of sensitivity and better s/n ratio down around 3.6/3.8 filament volts. Leutz was one of the first to write about it back in the 20s and his book Modern Radio Reception has graphs, etc showing the effect.

And C voltage can be pretty persnickety depending on the state of the tubes and if you're really picky there are noticeable differences at various rheo levels of A voltage as well as B+ voltage.

These are fun radios