[old_tv_nut]

Hard to tell from that picture - does it look ragged and changing like a torn fabric and comes or goes abruptly as the color is turned up, or stationary, intensity varies smoothly with color control and gradually fades out to the right?

If ragged, it's a bias/G2 problem, possibly fix by going through proper G2 and bias set-up procedure. I suspect this isn't it, because the white rectangle isn't showing it. Edit: try turning brightness and contrast to max to see if it appears on the white rectangle.

If stationary and gradually fades, it's a chroma smear. Maybe can be improved a bit by fine tuning.

It looks to me like the blue part is smeared too, which would also say a chroma smear.