Lexmark C510 Setup Manual page 24

Note:
Failure to collapse the green thumbscrews can
cause jams.
Set up the optional duplex unit
19
6
Pull the two green thumbscrews
out to extend them.
7
Push each green thumbscrew
gently toward the printer as you
turn it clockwise to tighten it fully. If
necessary, use a flathead
screwdriver to tighten the screws.
Then, push the thumbscrews
firmly toward the printer to
collapse them.
8
Push up the redrive assembly and
close duplex rear door.