1 Vertical lines on screen (moving "noise" lines)
They are transparent and only can be noticed with certain color backgrounds. Very small vertical moving "noise" lines at various places on the screen of my 27" late 2009 iMac the noise or flickering in the thin vertical lines seems to move upwards.
They typically appear as 2 or 3 lines next to each other with a very even distance between them, nearly exactly 1 cm. I've got a cluster of 3 on the left side of my screen, a few clusters of two in the middle and a few on the right side as well.
From my usual working distance of approximately 65 cm they are basically invisible, but from a somewhat closer distance of 40 cm they are very obvious.
The video card was affected by the big pink lines and “snow effect” issue and succesfully fixed with the “cooking the GPU in the oven” method.
But these lines I’m reporting here now have always been present before and after “fixing” the video card.
This makes me think it's a LCD issue.
I’m here to ask what this issue is (it is very difficult to take a shot):
Any help is appreciated.
1.1千 
2.6千 