Drill the marked holes in the F-785 backrest brace. Installo nutplates, drill the rivet holes and deburr. Rivet the nutplates on the backrest brace. Rivet the F-766 bracket to the channel and install the flap motor in the channel, install cotter pin. Bolt the motor to the WD-613-EF actuator arm, using washers to center it in the clevis. Safety wire as shown in Detail E DWG 33. Reinstall F-766 assembly in fuselage.