@bethzilla … the horizontal lines and double image flickering is caused only by a failed/failing tab gate driver on the lcd panel. to correct properly would be uneconomical to do so as the displays are the majority of a cost of a tv. you can try this method here to see if it helps:
https://www.youtube.com/watch?v=j7vl7-vZEL8
alternatively, you can disassemble the unit to gain access to the displays tabs and gently touch them to try and illicit a response. if one or many change the display at any point, you can try to use some foam to apply pressure when reassembled. follow this guide here:
https://www.youtube.com/watch?v=LysMj2Tcp4M
to be honest, these attempts almost never clear the issue. (sometimes with less severe cases it works) youre looking at a new set i.m.o.