Lexmark CX725
Remove the waste toner bottle.
Remove the motor cover. See Motor cover removal.
Remove the scanner rear left cover. See Scanner rear left cover removal.
Remove the right cover. See Right cover removal.
Remove the three screws (A).
Pull the mounting assembly away from the printer.
Disconnect the sensor cable (B).
Release the two tabs (C) from the mounting assembly, and then remove the sensor.
Lexmark CX/CSx2x and XC/Cxxxx: Paper Size Detection Is Incorrect due to Tray Configuration Issue
Manually assign a specific paper size not available in the printer paper menu.