I have an old Sony LCD SDM-S81 that worked fine for me for a couple weeks after
I got it used. Today, I found it displaying pictures badly, distorting the
colors by seemingly greatly exagerating the intensity of colors in areas with
changing shades of colors (Photos and Video, mostly). Additionally, the colors
seem to flicker, as if the problem alternates at a high rate.

Can anyone give me any advance clues as to what to look for when I open it up?

It is the monitor. Plugging in my old CRT shows no suck problem.

Thanks.