There are only 2 screws that hold the actuator in place. If it is making noise, the the actuator motor is OK, but the connection between the motor and the flap may be broken.
NEVER run the motor without having it connected to the flap!!! That will break the stopping points inside the black box!
If this flap has a plastic connection which broke, try to find the pieces and JB weld them back together. Then try to wind something around the plastic, like a hose connector, to keep it in place. Replacing the flap is not much fun!
When you put the motor back, make sure the flap is in the same position when you removed the motor.

Klaus