A few months ago, in the process of moving, I misplaced my imac's power cable. I've since been using a standard black comuter power cable, but it's finiky! If I tilt or move the screen, the cord unplugs itself. I am about to purchase a wall mount for my imac that will allow it to pivot and pull out from the wall... however, I don't have a lot of confidence is this black cable. Does Apple sell replacement cords online? If so, where? I am having a hard time finding it.