Problem with 13KC10 Zenith

[Carmine]

The set is a 13" solid-state color Zenith, built in 1976. The set belongs to my grandparents, and there's an interesting story as to how they "bought" it, but I'll get to that at a later time. I'd like to get it working again for them to use on the screen-porch.

Here's the problem...

All of the channels come in as if the fine tuning were set WAY off, in the direction of an overloaded signal. (Or as if the AGC was turned way up). Sound is normal. This is the "best-case" senario.

More often, it produces almost no video at all (sound is always ok)I took the sheilding off the tuner and gave it a major cleaning with contact cleaner and a toothbrush. I'm sure this helped, but it didn't fix the problem. Same problem occurs on VHF & UHF.

Then I tried the AGC adjustment. Didn't change anything, but the sound did start to buzz a little at the end of the scale.

At one point, I was able to get some video, and snow on the blank channels. However both the horiz and vert sync were very unstable.

This leads me to think it could be the AGC/Sync board, but I also think it could be an IF problem.

I've removed both boards, and cleaned contacts, etc. No change.

What are your thoughts, and how hard/expensive will it be to get parts? I'm nowhere near as much a TV expert as most of you, and my solid-state abilities mostly involve banging on things.

Condition of the rest of the set, including the CRT is excellent.

Here are my thoughts on going to Wal-Mart to buy them a new set...