Dell 5100cn Color Laser Printer - Manual (Page 223)

8. Tighten the three screws on the controller card from the back side of the printer. The two screws on the upper side
are different in shape from the one on the lower side. Be careful not to confuse them.
9. Reattach the paper tray cover to the back of the printer.
Removing the Optional Hard Drive
1. Make sure that the printer is turned off and unplug all cables including the power cord from the rear of the printer.
2. Pull the paper tray cover so that the top edge tilts out, then lift the paper tray cover off its hinges.