Hi I had my 24" LED screen replaced at my local Apple Service Provider due to a speck of dust. The technician was insistent that the screen need only be replaced and not the whole unit. Well I received the unit back today, and I'm sure my eyes were not deceiving me as the screen did not appear to be a LED screen. The screen does not appear as bright as before and the text not as sharp. Secondly, the heading in Display preferences says iMac, and the native display profile also says "iMac", no LED Display profile at all. Any thoughts.