Mad,
I had a weird problem once with a mag monitor where the screen would get wavy. I think I had an old 968... anyway I unhooked the monitor and put another vidcard in and it did the same thing, so I thought it was the monitor and I went out and bought a new monitor and set aside the old one. Well sure enough when I hooked the new monitor up it worked!
Great so far right? well 3 months down the line it started doing it again! ON the new monitor!! so I still had the old mag and I hooked it up to another computer and to my great surprize it worked fine (it still does to this day)! something in my video card had gone out and was causing some feedback or something that messed up my monitor but only for a while.
After the new monitor sat for about 3 days it ran fine... very weird! I don't want to scare you or anything but you can try the monitor out on another computer and see if that helps. (BTW for a while I could Degauss and it would stop waving, eventually it wouldn't help though).