Dell H815DW User Manual page 466

7 Gently lift the printer off the optional 550-sheet feeder, and place it on a level surface.
WARNING:
Two people are required to lift the printer.
8 Insert tray1 into the printer, and push until it stops.
CAUTION:
Do not use excessive force on the tray. Doing so could damage the tray or the inside of the printer.
466
Maintaining Your Printer