When you flip the main cover up, and flip the CD/DVD tray down, look at the cartridge color guide label (the colored dots). See the LIGHT CYAN dot? Directly across from that dot around underneath the gray cover is supposed to be a little plastic fin. That fin pushes the sensor switch in the CD/DVD tray to let the printer know if it is open or closed. If it breaks off, then the printer always thinks the tray is open. If it's broken off, you will have to either stick a toothpick or something into the switch, or glue a new thin piece of plastic in its place.

Hi there
this is the little flip lid that come open in the front of your printer it for printing on CD/DVD/ disk all you have to do is close it by fliping the the lide up.