I would use a towel to cover the drain port to prevent a dropped screw from going down the drain. Also, another method is to use a plunger in the reverse mode where you gentle press down and then quickly pull up to create a suction to dislodge the hair clog and pull it toward the shower drain. Make sure to cover the over flow vents on the stopper lever plate to allow for a good suction when using a plunger.