Lg tv horizontal lines at the bottom of the screen occurs repeatly

Hi, i have lg lm660s 42 inch tv. I bought it in late 2013. Recently, about 30 minutes after turning on the TV, lines appear in the lower half of the screen at five-second intervals. the part where the lines come out slides slightly upwards and vibrates. I want to know if it can be repaired. What could be the source of the problem? I am attaching a short video about the problem below. thank you.