It's quite likely that some of the internal pieces inside the disc drive have been broken or have become misaligned. To find out you'll have to disassemble the disc drive and remove it from the outer metal case. You may have to compare it to pics online to see if anything is broken. There is a metal arm inside that often becomes dislodged and can cause the problem you are describing. If you can post some pics of the inside of it I can help more. Unfortunately I don't have any pics of video of how to do this at the moment.