Brother HL-4040CN Service Manual page 183

(4) Remove the Front cover release button and Button spring from the Hook cover.
Front cover release button
Button spring
Hooked
(5) Release the two Hooks to remove the Front door Main from the Front door unit ASSY.
Front door main
Button spring
Hooked
<Right side>
Fig. 3-97
Front door unit ASSY
Hooks
Fig. 3-98
Front cover release button
Hook cover
3-75
<Left side>
Confidential