Chromacolor II color/tint issue

[TinCanAlley]

Lately my set has been twitching in the tint area. Going from more green to more red. Every now and then it will go almost completely magenta. If I turn to a channel with no signal (snow), there will be bursts of blue and red color snow over the screen. In the past the snow was always black and white.

I know there's an adjustment somewhere in the set (I have to find my SM) that sets the cutoff or something so color doesn't make it into a black and white signal (snow). If I'm remembering correctly, it seems this board would be where I should be looking?

I've checked all the knobs and cleaned them with Deoxit and the problem is not affected by manipulation of any of those user controls.

Other than the unstable tint and it going magenta, the set works perfectly.

Thanks!