Chosen Solution
I have a LG 55LV550 that has purple,green and blue fine vertical lines. I have already checked and cleaned connections. I also tried a replacement T-Con board but still the same issue. I also tried another set of identical ribbon cables from main board to t-con. Any other ideas. See picture.
@dandf22572 that looks like a memory error. Could be a main board issue or a panel issue (Sources drivers on LCD driver board which is part of the panel). Start with the main board. Then check the driver board ribbon cables where those enter the panels see if you find any corrosion etc.
