Vertical Lines on Half of Display

I have Acer Aspire S5-391 Laptop that has been working great for last 2 years. Recently the right half of the display intermittently shows only vertical coloured lines (very thin lines). Left half of the screen is always fine. When the problem occurs, I can manipulate the screen a bit (physically by slight movement) and the problem usually goes away. Slightly twisting the screen seems to do the trick. For this reason I think the problem is likely in the display, not in the video card or motherboard.  When External Monitor is connected there is no issue at all.  It is always right half of the display.

Thanks in advance for any advice.

Ravi.