Television and Home Theater

My Sony 32" KV32V65 TV has developed a problem. When first turned on everything works fine. After about 5 minutes the picture starts flickering and finally diminises from top and bottom. Audio is still working. If I tap cabinet the picture will sometimes be restored for a few minutes and then go out again. This TV is about 8 years old and wonder if it is wise to try to repair it or just part it out to anyone looking for Sony parts? Any suggestions or tests will be greatly appreciated. Thank you.

i have a 15 month old 42" visio edtv - they say is plasma ??? turned it on yesterday - i have sound and can change the channels but NO picture - even when i disconnect my dish box i do not have any snow or OSD on screen direction - like when i used to change the input i would see blue words at the top right corner telling me the choice rgb... but now nothing.. the screen is black - i feel like it is a bulb or video board??? i have the manufacturer sending me the schematics manual. i have taken the back off to see what i am dealing with - looks like a big mother board.

The picure and sound are cutting  in and out on my Philips 28PW6005/05 widescreen TV. The channels also seem to be changing. When I switch it off it sometimes works for a short while.

Can I repair it myself and how.