Took off the casing on my 1640 last night. I noticed the white wheel with teeth wasn't engaging the adjacent piece of plastic with teeth. The first little notch on the plastic was worn down about half way, so the wheel would just spin around and not grab it. I noticed sometimes if I really push hard on the left side of the tray, sometimes it grabs and then ejects.. but its not consistent. Even if you use the manual eject, the drive never gets raised - because that is controlled by the notched plastic moving over - thereby making it useless.