HP QMS 1660E - Manual (Page 147)

Media Input
Options
6-13 Printer Options
2 Load the paper in three steps as follows:
3 Ensure that the paper stack lies flat, does not exceed the top
limit mark, and is positioned under the retaining clips.
a Up to the bottom limit mark
b Halfway to the top limit mark
c Up to the top limit mark
Top Limit
Retaining Clips