Q Our iMac late 2009 27” has recently had problems with its optical drive that were not relieved by upgrading OS X. The drive now refuses to read most disks, normally spitting them out even though the disks have usually spun up inside. What is wrong with it?
A As this has persisted through a major system software upgrade, it is almost certainly a hardware issue, rather than corrupted drivers.
At its simplest, it may just be that the lenses inside have become grubby and need a clean. Visit your local HiFi store and purchase a gentle optical drive cleaner which uses minimal fluid; obviously flooding the inside of your iMac with cleaning fluid would not be a good idea, nor should you use anything abrasive.
If that does not help, the drive probably needs to be replaced. It is then important to use the proper Apple kit, which contains a pair of replacement internal plastic shutters to keep dirt out of the drive, so you may wish to get it done through an Apple store or official service agent.
As a temporary workaround you can connect a basic USB optical drive, although that may not play DVD movies as readily.
Updated from the original, which was first published in MacUser volume 28 issue 20, 2012.