Zenith 4-tube hybrid Chromacolor questions

[RetroHacker]

Well, I've been out of the "game" for a while, haven't been seriously collecting TV's, although I still have my collection... just haven't been actively hunting them in a while. But, last week, I found this Zenith Chromacolor out at the curb, and it followed me home.

The set is fairly dusty, but not bad overall. No major burn marks or signs of horrible failures, so I powered it up. Sound works, no picture. I can hear the horizontal section running, but it sounds "off", probably not the right frequency. I'm getting about 700v on the output of the flyback once the tubes warm up.

I know these sets are famous for burning up triplers, and it looks like the focus divider has been replaced before. Just for grins, I tried swapping out the 6U10 since I had spares, and no change.

Now, I'm not sure which model this actually is. The back cover, on the inside, lists 19DC10,11, 12, 18, 21, 22, but nothing on the chassis itself clues me in as to which of those it actually is. How do I tell? Also, I don't have the schematic for it yet, but I'm probably going to go dig that up soon.

Any advice? I haven't really worked on one of these hybrid sets in a long, long time.

-Ian