If your Mac’s SuperDrive keeps ejecting discs after trying to read them, this may be a sign that the drive is on it’s way to certain death, but it is more likely that the drive has accumulated dust that is interfering with its operation.
First, make sure to examine the disc(s) in question for any damage or smudges. If it is smudged or dirty, use a soft cloth and use left-to-right wiping to clean it. Never clean a dis in a circular motion.
If the disc(s) seem to be okay, it’s time to work on the SuperDrive. Shutdown your computer and get a can of compressed air. Place the tip of the nozzle attachement where it is aiming inside the drive and give it a couple of quick blasts to blow out any dust particles that may be causing you issue. Power up the system and give it another try. Most times, this will be enough to get the drive functioning correctly.
If the drive still continues to toss your discs back to you, you can purchase a CD/DVD drive cleaning kit for approximately $15 and use it to clean your drive. The cleaning disc will get ejected (just like your discs were) so continue to insert it a few times until the drive is clean. Try your discs to check drive functionality.
Hopefully, one of the above steps has fixed the SuperDrive and saved you an unnecessary purchase.