Zenith 19L25 Chassis Restoration - Advice?

[RitchieMars]

Well, I just got back from North Carolina today and got some things in the mail. I got my attenuator, a 12BY7, and a 6AU6. I've tested the set after installing both tubes and the attenuator but not adjustment seems to remedy any of my previous problems. The sound still distorts and buzzes pretty bad on most channels, and I have very little contrast. Back to the drawing board, I guess. I'll be pulling the chassis back out and going over the video and IF section again following some suggestions I've heard here and see what I can find.

UPDATE: By the way, that fringe lock control caused a sudden pop again last time I tried adjusting it. I'm not sure what it is. It sounded like something arched and there was a flash inside the set, but no burn smell and no change in performance. It has NEVER done it other than when I've turned the fringe lock to a certain spot. Pretty unnerving...