Oki ES3640MFP Component Replacement Manual page 42

5.
Release the hook that secures the sensor holder to the feeder.
6. Turn the sensor holder over, and then release the hooks that secure the sensor to the carrier.
7.
Disconnect the sensor connector.
Tray 1 No Paper Sensor
1. Remove the Tray 1 Paper Feed Unit.
2.
Remove 4 (metal, 23 mm) screws that secure the cover.
3.
Release the hook that secures the No Paper Sensor housing to the feeder.
4. Turn the housing over, and then release the hooks that secure the sensor to the housing.
5. Disconnect the sensor connector.
Tray 1 Feed Unit
Sensor Cover
Tray 1 Feed Unit
Tray 1 No Paper Sensor
Tray 1 Feed Unit
Right Lower Door Detect Switch