Text is out of focus

My RCA 56" HDTV is about one year old. All the text that shows up on the screen is out of focus or blurry. It was fine the night before. I went in and reset the auto convegance, and everything matches up fine. It's not my cable box, because I disconnected it and the channel numbers and menu text is still hard to read.

Behind the front grill is a door with 4 t20 torque screws in it, remove that & to the left will be a screen/focus block, three knobs will be for tube intensity STAY AWAY FOM THOSE. the other three will be your focus for each tube