Lexmark T640 User Manual page 85

23x and 24x jams
Paper jams in these areas can occur on the incline surface of a tray or across more than one tray. To clear these areas:
1
Open the printer paper tray, and remove any jammed media.
2
Open the duplex tray.
To remove the media, pull up.
Clearing jams
Clearing printer jams
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