Okay, back to this. Now there is substantial progress.
I never could get the colors right on that k7000. The best I could get was back to where the original chassis was to begin with. Probably spent 3 hours just on color adjustment. I couldn't even get a pure white without a video signal - it never got closer than a grey/blue.
I even tried swapping out the game's color board. Berzerk isn't actually generated in color, it passes the game signal through a small PCB that adds color before it gets to the monitor. It was originally intended to be a black and white game but they correctly recognized that with color games hitting the market they better get Berzerk in color too or nobody would buy it, speech or not. The change in color board didn't change a thing.
At this point I decided if the problem isn't in the color board... and it's consistent across two chassis... gotta be in the tube. I put forth some effort to find a full replacement monitor but although I would usually get several responses to WTB ads nobody would ever actually set up a time for me to show up with cash in hand. Got fed up with that, too, and I don't ever plan on having many raster vids...
So I decided to check out the scan converter sold
here. Some forum searching turned up one solid positive review and a lot of posts asking if anyone had bought one. I bought one.