My rear projection tv has
This was posted a long time ago, and by now you've probably dealt with it, but the line you describe sounds like retrace blanking being visible. In any case, this might help someone. As the tubes age, the screen voltage needs to be adjusted, which is simple. Behind the right side speaker grill is a panel that covers the screen and focus adjustments (screens are 3 screws along the top, Focus are 3 below them). From left to right they are for red, green, blue, both top and bottom. With no video input and the PIC control set to PRO (whichwill make brightness, contract, etc at 50%) and in a dark room, in your case, turn the top left screw left and the line should disappear. Then turn it right until the line just appears and left slowly until just after if becomes invisible. Normally you'd do this for all of them, but just do one at a time. That's because when you adjust it, the convergence will need to be adjusted. The right way to do that is to go into the service mode and do it manually. I don't know if the "consumer" flash focus will get you back in line or not, but you could give it shot. If you're not familiar with manual convergence, it's not that it's extremely difficult, but is time consuming. Plus since you'll only have to do the red, you have a shot at it even with minimal experience. Good Luck.