Avery Dennison Monarch 9855 Operator's Handbook Manual page 28

The shelf must be parallel to the platen roller, not at an angle. See the
following diagrams.
CAUTION: Make sure the shelf is not misaligned with the platen roller, or
damage to the platen roller could occur.
2-12 Operator's Handbook
Shelf inserted correctly.
Shelf not inserted correctl y.