Some background: This is a iMac 24'' Early 2008 model (according to mactracker). The monitor itself is a replacement - the factory panel failed while the computer was under warranty and was replaced by applecare. In the last 7 months it started developing this pattern at the top of the screen just below the camera: Any idea what it is? Is it easy to repair? (i.e. maybe dust?) Thank you, Nikos.