I was about to burn a DVD but I could not insert the DVD disk into the optical drive. The disk itself was allowed inside only a few centimeters but something stopped it and there was no mechanical sound of any sort from the parts that take the media inside the drive. What I had previously done was to install El Cap.The OS itself works well, the burn ISO is now integrated into finder (and CLI) instead than Disk Utility. So after googlein about i noticed folk with similar problems so i tried some PRAM zappin and so in but it didn’t work. Then I went over to ifixit.com for some tear down instructions and opened up my computer to have a look at the drive. I had to unwrap it from some plastic to get inside to the mechanical parts. After trying to figure out how it worked I dared to move some parts – nothing was broken. I took a CD and recreated an insertion. The parts did what they should. After resembling I rebooted and the drive worked again. It must have been a mechanical part that got stuck from a software instruction. I don’t use the drive much either so i guess its lack of exercise.