I recently purchased a used MacBook Pro 15" Retina (2012). Before I bought it, its screen was replaced entirely and so was its upper case. I am currently using Windows 10 on the laptop.
I started noticing intermittent vertical lines 1 pixel wide when using the machine. At first I thought it was a row of dead pixels, but the screen will sometimes go back to working properly for no reason what so ever. Sometimes the lines are a bright magenta or dark green. The most persistent line is a very subtle light gray. I take very good care of my electronics and I have never dropped the MacBook. What do you think could be causing this? I believe I am past the previous owner's 90 day warranty on the last repair and the AppleCare expired about a month ago.