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I have like 4 or 5 front PCBs I've come across over the past year or so that have this issue, and I have no clue what to do to fix it, if there is a way to fix it. Have any of you come across this issue and know what to do with it, or at least have any ideas as to what it could be?
Some of them have gotten like this shortly after peeling the film off the backside of the LCD, so I figured I was maybe too rough with the ribbon cables, but after thorough inspection they seem fine, and I've also run into a couple of systems that have this issue before being opened up or anything. On a couple of them depending on where you have the contrast dial set it shows some faint lines on the screen that get ever-so-slightly lighter or darker, as pictured below.

Any idea how to deal with this?