HP LaserJet Pro M435 Multifunction Printer series - Manual (Page 40)

4. Select the Print on both sides (manually) check
box. Click the OK button to print the first side of
the job.
5. Retrieve the printed stack from the output bin,
and place it with the printed-side facing down in
Tray 1.
6. If prompted, touch the appropriate control panel
button to continue.
32 Chapter 3 Print ENWW