Toshiba 50" projection TV - Vertical Picture problem

My Toshiba 50H12 projection TV have the following problem: The top half of the screen keeps going black for a few seconds or a whole day. It seems the top portion of the screen is condensed in 2" band in the middle of the screen. The problem keep coming and going, could this be the Vertical output IC? I have experience repairing electronic circuits boards and I can’t afforded a new TV at this time please help