Oki ES3640MFP Component Replacement Manual page 43

Tray 1 Registration Sensor / Feed Out Sensor
1.
Remove the Tray 1 Paper Feed Unit.
2. Remove the Registration Clutch.
3.
Remove the Feeder Board Cover.
4.
Remove 4 (metal, 6 mm) screws that secure the feeder top.
5. Separate the feeder top and then turn the top over.
6. Remove 2 (black, plastic 10 mm) screws that secure the sensor housing.
Feed Unit (Top)
Tray 1 Feed Unit
Feed Unit (Top)