Replace drives in lite on 5116, 5116, 9016?

I have three lite-on dvd recorders. Two of the work only so-so. I know that I will have to replace the dvd drives soon or change out to another recorder. All of these units are great and I would like to keep them going as long as possible. I’ve heard that changing the dvd drives out in the 5005 is easy but I opened the 5115 and it doesn’t look like its just “unplug and replace” Anyone have any info on drive replacement for the 5115, the 5116 or the 9016? thanks!