It is a Proscan 50700 from around 1998.
Here are more images of what the picture looks like. If the OSD is on different RGB pins of the IC, aren't both images projected from the same tubes? I haven't disassembled the TV yet to take a look at the physical tubes. I am moderately okay with basic electrical/electronic/mechanical things but I've never worked on a TV before and wouldn't know where to start.
Any ideas what the culprit behind this is and if it is worth fixing? Could it be as simply as coolant fluid replacement?
