HP LaserJet 1015 Printer - Manual (Page 41)

ENWW Printing on both sides of the paper (manual duplexing) 33
4 Gather the printed pages, turn the printed side down, and straighten the stack.
5 Place the stack back in the input tray. Side one should be facing down with the bottom edge
feeding into the printer first. Replace the priority input tray.
Press the Go button, and wait for side two to print.