Lines across my MVS monitor?

I have been vacillating on whether to ask this here, but since I can't seem to figure it out for myself, here goes. The monitor for my MVS seems to have thin, white, horizontal lines that overlap the graphics of whatever game I happen to be playing. When I first turn it on, they don't show up, but after a few minutes of being on, they show up quite clearly. It is getting rather annoying, and I am wondering if anyone else has had this problem/knows what I can do to fix it? I'm hoping I don't have to buy a whole new monitor, as that will get rather expensive. Many thanks to whoever can help.

One (or both) of two things

1. Screen voltage too high, thats the adjustment above the focus pot. CAUTION-VERY HIGH VOLTAGE.
It should be backed off so that the retrace lines are not visible. If set too low there will be flairing of peak whites or rgbs.

2. Cap kit, if the capacitor that decouples the supply to the video output stage has dried out you can get a similar effect.

These are the caps required for a full cap kit on various monitors.

http://www.ionpool.net/arcade/capkits/capkits.html

If your not shure what a cap kit is, good info here

http://www.alsarcade.com/capkit.htm