Well, I dove in and have located what appears to be the problem. Where the ribbon from the logic board to the screen connects to the logic board, it's a tall, thin connector. It wiggles ALOT. So, I used the advanced pressure-application method (stuffing some tissues between the connector and something solid inside ) and that seems to have alleviated the problem to a great degree. It still freaks out at times, but now when it does, leaning the screen back all the way seems to correct it.

Thanks guys for helping me to save this wonderful little PowerBook!

/me goes back to playing WarCraft II on it