Hello, all! I have searched every post about lines in the TV, but not one of them seems to be the same problem I am having. It is not really "lines" as much as a big section of the TV darkening and lightening at perfectly timed intervals. About 1/2 of the screen from halfway down to just shy of a couple inches from the bottom will darken (not black, just darken the current picture) and shift that piece of the picture down about 1/2" then after about 3 seconds will go back to normal. It will stay normal for about 3 seconds, and repeat. The 'flashing' of darkness does not speed up, slow down, get larger or smaller... just perfectly timed intervals no matter how long the TV stays on. I know one of the boards has to be bad, but I don't know if it would be the a) power board, b) LED Driver board, or c)T-Con board. I could buy all three for less than a tv service would cost, but I would like to only have to replace the ONE that may be causing this issue. I cannot find a description of my issue on any of the troubleshooting documents of forums, so I am hoping the unique nature of the flashing dark section will lead someone on here to know which board is the most probable culprit. Thanks in advance for any feedback you may have.