Use the following procedure to attach the Z-fold support tray for finisher to the finisher upper tray.
Press the [Suspend/Resume] key.
The key lights up, and printing stops.
Remove the prints.
Set the Z-fold support tray for the finisher shift tray.
Attach the Z-fold support tray by inserting the two pegs on its underside into the two holes on the finisher shift tray.