I would get 8 solid color images: white, black, red, blue, green, cyan, magenta, yellow and use a simple slideshow program to display each for say 15 seconds, let that run for... 15 min at a time, stopping if you see results.
I'm not 100% certain it will help, but if the only other advice you're getting anywhere is "buy a new tv"... it can't cause any outcome worse than that, can it?