I have white(!) 20" iMac, but now the screen just won't stay in position i want. like, if i turn my screen to look totally up, after a while it goes down looking totally down. I want it to stay in fixed position. But it does not! Son of a !!! Visual example: So, any suggestions on how to fix this thing? Whats wrong with it ... Can i even fix it at home or should i just spend a lot of money on this ... THING ... and let some pro fix it!