Hey, Reece. I spent some time today going over this again and I was finishing up some work I had planned weeks ago, but I was waiting on my parts to arrive. Yesterday and today, I installed the line filter capacitor, replaced a capacitor that had tested as shorted, and replaced any resistor which seemed out of spec. There were actually quite a few, and by more than 20%. A couple had doubled, and even tripled in value.
I couldn't figure out my pots. I looked for a hole to drip the oil through, but they seem pretty closed up. Here's what they look like...
I only tested the radio once today, and I never heard any static turning the knobs around. The band selector/phono switch has no static, either. Just a soft thump when I switch it back and forth. When I turned it on, I actually heard a repeating thump when tuned to a certain spot on Shortwave. After about a few minutes of it running pretty quietly, that static came back which crackled and roared, even on phono and even if the knobs aren't turned at all.
Not sure if I have a tube bad or not, but it gives me the impression that something's causing static once the radio heats up for a few minutes. I also noticed that I get about 28 volts AC from the chassis to ground whenever the set is plugged in now. I hope I got the line filter capacitor right...
I installed it as I could best understand from what I read on JustRadios. It's connected directly to the "hot" side ( small side of the plug ) and then to ground, which in this case I used the unused ground terminal.
Anyways, I'll try checking around that 7A7 tube tonight and see if i get some noise from pin 6 as you mentioned, and I think far as alignment goes, I'll probably have to pull apart my Zenith H724. I have a schematic around from when I recapped it awhile back. It doesn't pick up AM extraordinarily great... there's lot's of noise over every channel... but it's probably the best choice. I also have a Zenith K731 but I can't get the knobs off the front to get it open.
Thanks, and I'll keep checking back on this thread. I spent about 4 hours today working on that chassis, so I'll probably take a break for awhile tonight!