Help: Display on 4000 cuts in and out / very "liney"

Title pretty much says it all. It otherwise functions normally and sometimes the screen works but it's almost like something is loose or dusty in the display. Anyone have any suggestions as to where to start when trying to fix it?

Theres a thread around here somewhere that describes your problems. Im not sure which is which, but if the lines are vertical, a cable is loose. If the lines are horizontal, your display is going out. Im not sure ill try to find the thread also.

Does it look like this?

viewtopic.php?f=2&t=159720&p=1503133&hilit=Lines+in+the+display#p1503133

It's actually more like the photo on this thread: viewtopic.php?f=2&t=129508

I actually recall fixing it once but then it started happening again. I can't remember what I did though but it involved disassembling and basically blowing on it and wiggling shit around.

In that thread they say it was a loose cable.

I've read it can also be a faulty display, I hope that isn't the case. It almost seems like it could be related to the contrast button too