Newb with 70's Quasar Vertical Hold problem

[Cpalmer]

First of all, sorry for the long post!
This might be something that could be easily searched, but I really don't know where to start. I bought a cabinet style TV last year with the intentions of only using the hardware to install a new flat screen. However, I tested it out and found that the TV had a great picture already! Unfortunately, the vertical hold will not stay correctly adjusted. If you try and adjust it over a period varying from about 10 minutes to an hour or two the vertical hold will fall out of adjustment. I have a basic familiarization of electronics, I repair electric motors for a living, but Im a rookie when it comes to TV repair! Im at work right now, but plan to post pics tonight so everyone will know which TV I have. I believe it was made around 75, there was a sticker someone ripped off that covered up the Motorola address on the rear, I've heard that was done around the time Motorola sold off their Quasar line of TV's