I would get a 3.5" drive cleaning kit and with some alchohol and run it on the drives. Surely they are dirty. I would also open the metal shutter and inspect every disk surface for any dirt or mold, etc. and make sure the disk surface is clean before using! Disks will gum up drives and make them not work, happened to me before. I had to clean all the drive heads vigurously before they worked again. Other than this the only thing I would suspect is the drive is bad or the disks are just bad. I don't think the A600 MB can go bad in something like this, but its know to happend.
