After you check it with an external monitor, if the external shows the same problems, call Apple for a free logic board replacement for the Nvidia 8600 GPU issue. You may still be within the 4 year limit Apple set on this or be able to get an exception because it is so close. Here's Apples notice on this along with where and how to contact them: http://support.apple.com/kb/TS2377
Connect to an external monitor if the lines are missing from there it' might be the controller board for the LCD. I'd replace the entire display as futzing with the controller board alone is a lot of delicate work...Once you get the back off the display you can find the right part number for the screen.
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