need help diagnosing mitsubishi ws 55908

my big screen tv is about ten years old and is starting to act funny. last month the picture started to glitch when i turned it on. the picture would come through but warped like a bubble picture. it would be like this for a few seconds before giving a normal picture. the problem has been getting worse and looks like its becoming more of a permanent issue. does anyone know what part seems to be malfunctioning. and how id go about fixing it. its not the connections because it is on all videos. color seems fine. just getting a distorted bubble picture.