So I got a new CRT pickup off the sidewalk and I really like it. I just modified it for S-video...BUT it hates being tated

It doesn't appear to have a degaussing coil inside, which is usually fine. But when I turn it sideways to play shmups the thing has like a rolling degauss problem...its weird. The colors change with a slowly moving horizontal line ?

This issue seems to go away as soon as I put it back to regular position.

I'm concerned there might not be a way to fix this since it doesn't seem to be a power on degaussing issue, but a constant degaussing problem whenever it's tated.

Any tips?