Is this Zenith worth the effort?

[jstout66]

I was worried about that, and was watching this thread to see if a tuner issue cropped up. Those electronic tuners could be a pain in the ass, and were showing problems by the late 80's. It's Electronic, so there is no cleaning.
Start with the obvious... turn the AFC off, tune it in to the strongest signal/pix/ turn the AFC back ON. If it still has the problem, the tuner is a module, and you'll need to replace. If that's the case, let us know which one. It's listed on the schematic.