Lisa new start - Screen line

@dougbarker a single white line is commonly caused by a failing vertical deflection. On your device, this could be caused by failing electrolytic capacitors. I would suggest that you recap all of the boards for now. Clean those boards before recapping and check for corroded traces as well. It might help if you can post lots of good pictures of the boards etc. with your Question. That way we can see what you see. Please remember that you are dealing with a CRT and those carry some powerful voltages. You definitely do not want to poke around in those unless you are fairly familiar with working on them. At minimum read through ESD Safety Guide this document.

Adding images to an existing question