To get those screws out right you really need to pull the blower box out , what I have been doing is using a small pair of locking vise grips grab the threaded end of the screw that sticks out into the vent and start turning it till the head of the screw hits the frame of the machine then wedge something in between the louver and the frame so you can grab the head of the screw with the pliers and turn it till you get it out , then use small plastic wire ties thru the holes to hold it in
