I have a Mid 2013 13" MacBook Air and the hinge is broken, meaning that it will fall almost flat with the keyboard. Also, whenever I adjust it, the hinge makes alarming sounds . I'm guessing that this was probably caused by longterm stress on the hinge throughout the almost 4-years I have been using it. I'm wondering how much it will cost to repair it, as the Air is out of warranty. If anyone has who has experience or knowledge can inform me about this, that would be great .