Monitor Problem

Okay, well ive still got a crt, its quite good one (sony) so its lasted a long time.

Today ive noticed that sometimes the screen flickers abit and the gamma flickers aswell - this is on desktop so i dont think its my graphics card over heating or anything.

So my question is, what else could be causing the probelm, is it just my monitor coming to the end of its life? Or is something else to blame?