Horizontal Lines on TV

I'm gonna give this TV which I gave up on a while back due to a lack of time a last chance. It's a Toshiba Smart TV with the model number VES500QNDP, with a Vestel 17MB170 mainboard in it. The problem is that the TV has horizontal lines going across the screen. These lines are less noticeable when the TV is first turned on, but get considerably worse as it warms up. I've already tried replacing the mainboard with no luck, my only other idea would be the T-Con board. Any help would be greatly appreciated. Thanks!