Vintage Zenith Snow

[sgtrob]

Hello all! I have yet another perplexing problem with my 1972 color Zenith with the 25CC50 hybrid chassis. The problem is, well SNOW, in every condition of operation. Even with a DVD player hooked up directly to the TV, I just can't get a clear picture, there is still snow. I have done all of the prelimaries, I changed both of the tuner tubes, and the 3rd video IF amplifier tube, the rest is transistors (havent messed with those). I tried fiddling with the AGC, this had no effect. I even cleaned the tuner contacts, nothing. I am actually a bit lost right now. Anybody have any experience with this problem on this chassis?