Lexmark 5021-0XX - Manual (Page 244)

4-14 Service Manual
5021-0XX
3. Open duplex rear door (A) and pull down redrive assembly (B).
4. Pull green thumbscrews (C) out and turn counterclockwise until
loosened.
Note: During reinstallation of duplex unit, ensure that thumbscrews
are fully depressed after tightening. Failure to fully depress the
thumbscrews may result in paper jams.