Greetings DAVID GEISSLER,
Welcome to the Apple Support Communities!
I understand that you are attempting to import all of your music from CDs into iTunes, but a lot of your CDs are automatically ejected from your iMac. In this situation, I would recommend the troubleshooting steps in the attached article to help resolve the situation.
Get help with the slot-loading SuperDrive on your Mac computer - Apple Support
Accepts discs but they don't mount or are automatically ejected
- Make sure the drive is not placed upside down. The aluminum enclosure should be facing up as shown in section 1.
- Check the disc's surface for scratches and dirt, since these things can prevent the disc from appearing on the desktop.
- Connect the MacBook Air SuperDrive directly to the computer's USB port instead a USB hub.
- Reset the System Management Controller (SMC).
- Ensure your drive can read the specific type of disc being used. The System Profiler or System Information may provide additional information regarding what media your computer supports.
- OS X Snow Leopard v10.6 or earlier: Open Apple System Profiler by choosing "About this Mac" from the Apple () menu. Then, click More Info.
- OS X Lion v10.7 and later: Click the Apple () menu and then hold down the Option key. Choose System Information from the menu.
- If the disc continues to not be recognized, contact Apple or an Apple Authorized Service Provider, or make an appointment with an Apple Retail Store.
Have a great day,
Joe