This sounds almost exactly the same as what happened to mine after about 10 hours. Boy did I freak, I thought I was going to have to ship the entire thing back! (big $$$!)
Anyway, they thought it was the neck board. So I replaced that first. That required using a razor to cut the rubberish sealant holding it on at the tube neck. It slid right off and I tried the replacement one (my replacement electronics were not brand new, unfortunately). I never put another sealer to hold the new neck board on. I probably should, but I need to find out if some regular silicone chaulking is safe to use, or what exactly I should use.
That didn't fix it. So then I (nervously) discharged the tube. No spark or noise happened, so I assume the auto-discharge feature was working as it should. Then I swapped all the remaining boards. There was really nothing tricky to it. I didn't even remove it from my game cabinet (thankfully - I wasn't looking forward to doing that since the thing is so heavy!).
It worked! And has worked fine ever since.
This really sucked for me because I had just got my cabinet all together and working and then the freakin' monitor died! It was so anticlimactic!!
Wade