Refer to section 8.3.4 Removal of the Top Operational Unit of the Service Manual.

Disconnect the Top Operation Unit ribbon cable if it was not disconnected for removal of the Main P.C.B. earlier.

Unscrew the indicated Top Operation Unit retaining screw while simultaneously pulling back on the top unit to keep the screw in its Top Unit hole and prevent it falling out into the camera. Once the retaining screw comes loose, pull the Top Operation Unit out while keeping pressure on the screw.