Hitachi Ultra Vision rear projection

I have a Hitachi Ultra Vision rear projection tv model #50ux52b that has worked flawlessly for about 10 years until a short time ago the video would flicker on and off or would change to a pin cushion picture in the center of the screen. This would happen several times back and forth and then eventually the video and audio would quit all together. The red power indicater light would still stay on. If I turned the set off for awhile the video will return but only for a minute or less then it would quit again. Any info. on what may cause this would be appreciated or is it not worth fixing from a monitary stand point. Thanx in advance