I have a Vizio Xvt553sv and on the screen towards the lower right I get a constant flickering. At different times in rectangle type box shapes around the screen the screen dims in those few areas. I had someone come out and look at it and they said the backlight was going out and that it would be better spent getting a new tv. I'm not sure if it is the backlight inverter or are their tubes in this tv that have gone out. Please help!