If the computer is up and running and you put a DVD or CD in the slot it goes 90% of the way in, but the drive never grabs it.
If you slide the disk in at start up, it grabs the disk and it will play and or install software, etc just fine and it ejects with no issues once mounted.
I have read the article you are referring to and except for the last step nothing really applies.
I am hoping for a better understanding of what triggers the drive to take the disc. It seems that mechanism must not be working correctly all the time.
I reset SMC last night to no avail.
Thank you for taking the time to help,