Apple ColorLaserWriter 12/600PS - Manual (Page 40)

4 Slide the photoconductor cartridge all the way into the receptacle.
Save the orange tray in case you ever need to remove the photoconductor for
troubleshooting.
When the photoconductor cartridge is
most of the way in, you can remove the orange tray.
15 Setting Up the Color LaserWriter 12/600 PS