My suspect are the color wheel(s). There's a YouTube on that but I can't tell if you have it fixed or DIY. Be aware this is just a guess.
I have a Samsung HLP508SW; have had it since 2005. Great set. Lately, some colors look smudged, sometimes. Very noticeable on skin tones, greens from soccer pitches, etc. Any suggestions on what could be wrong? Is it worth fixing or do I just bite the bullet and go shopping?