Cleaning of HDTV

My HDTV is about 3 years old. It seams no matter how I adjust it,
the picture is just not as sharp as it used to be. Is it possible that
it has gotten dirty on the inside? It is a rear projections set, with
7" guns. If those lenses have dust on them wouldn't that affect the
picture? Does anyone have any experience cleaning the inside of
a RPTV? What should a person use for cleaner on the guns? The
mirrors? The screen? Any help or advise is appreciated.

Hey swgiust, do a search for "Cleaning RPTV." You will find all sorts of useful tips and many can be performed by you in your home.