Found the source of the arcing sound...turns out the HV "doorknob" capacitor went bad. By chance I noticed it was really hot when poking around and so I pointed my IR thermometer at it and powered it up and the temp jumped up into the 150's almost immediately after the sizzling began. I unscrewed the 1B3 base from it and powered the set on (holding the tube up with a wooden stick) and sure enough, the sound was gone and I had 10000+ volts at the suction cup! Unfortunately, it seems that the only replacement I can find is one going for $40 on amazon X.X
still no progress with tracking down a new audio output trans. (though, I haven't really looked) but I have found a few kinda close (but not really) on oldradioparts.
with the picture tube removed, I decided to do a little cleaning on the chassis. I tried doing what Bob Andersen has done in a couple of his videos - paint on some Rustoleum rust stripper, wait a few minutes, then wipe it off with a wet cloth, and then spray on some DeoxIt. I first tried it on the area that would normally be hidden inside the HV cage and it turned out pretty well. Then I did it over the big empty area under where the picture tube sits and now that whole area has developed a uniform layer of rust
did I forget something? I'd like to get the whole chassis all nice and pristine (again, I may be selling this one down the road) but I'm afraid to go any further. I also tried it on a small area on the side and, while no rust has formed (just slightly) the area seems to have gotten darker and sort of splotchy.