HP Color LaserJet Enterprise Multifunction M680 Printer series - Manual (Page 143)

4. Lift the tray up and then pull it straight out to
remove it.
5. If jammed paper is in the feed area, pull it down
to remove it.
6. Reinstall the tray, and then load full reams of
paper into the tray. The tray holds 1,500 sheets
of paper.
NOTE: For best results, load full reams of
paper. Avoid dividing reams into smaller sections.
ENWW Clear jams 131