Picture problem/1995 19" Zenith

[worm082]

I have a 19" Zenith Sentry 2 from 1995. Never had a problem with it. This week something has started with the picture.

If you turn on the set, it works perfectly fine for 5 or 10 minutes, then the picture slowly fades to black and stays that way (sound still works okay) until you try to do anything (change a channel, raise volume) then the set just shuts itself off. Then it has difficulty turning back on for a while.

If you unplug the set and let it sit for a while it will again turn on okay/have a fine picture for a few minutes and the cycle repeats itself.

Any ideas on what's causing this? Is it a power problem? Is the tube dying? Something that's easily fixable? I'm a newbie to this stuff.

Thanks.