Oki ES3640MFP Component Replacement Manual page 85

6. Rotate the Top Cover Latch upward, and then remove the 1 (black, plastic 6 mm) screw that secures the front of
the Cyan LED Holder.
7.
Move the Cyan LED Holder to the right to allow sufficient clearance to remove the duct from the LED Assembly.
8.
Release 2 hooks that secure the diffuser to the duct.
9. Release the fan wiring from the guides in the duct.
10.
Release 1 tab that secures the Top Cover Fan to the duct.