Odd Chromacolor 2 problem

[jstout66]

I have a problem with my Chromacolor 2 that I have never run across, and I would like to know if anyone has run acroos this and what adjustment or module I need to be looking at. It's pretty minor, but has me confused. I have a rainbow pattern running in the background. It's barely noticable but IS there. You really notice it on a scene with a black background. The color is solid and not going out. The picture is perfect except for this rainbow pattern in the background. It reminds me of when the color killer is out of adjustment, except I have color. So do you think it's an adjustment, and if so what module would that be on?