This could be a sad case…… This sounds like an early VC1 that used a strange chip in the enhancer…. I have known of the problem and was only able to fix it by exchanging chips…. but this is a surface-mount chip and it’s not easy, and they are no longer available!
I never like to give up on old gear, but in this case I have to suggest that the green bin outside the back door might be the place for it. 😥