Mitsu HD 1080 series TV blinks between black and normal

My 5 year old mitsu 57" (?) HD 1080 series rear projection(?) TV works well except it has recently started to blink between a completely black screen and a normal screen. The blink only lasts for less than a second and as the TV warms up it can degrade to blinking on and off in rapid-fire succession. Sometimes the TV works fine for many hours and sometimes it seems to start as soon as we turn it on.

I've never opened it up, but if this is a simple part replacement I'd like to try it myself instead of hiring someone for big bucks to do it.

Any help would be appreciated.
JPR