I am not sure if this is how it is supposed to work, but whenever i put a DVD or CD into my mac mini, i have to push it in probably 3/4 of the way before it sucks the disk in, at which time it makes some sounds like it is hitting the back of the drive. It works fine, but on my iMac G3, it pulls the disks in slowly and doesn't make any sound against the drive. Is this normal?