The middle screw forces the clearance to open and the outer two pull it shut. If you unscrew the middle screw do you still have too much free play or does the saddle lock up?
If you still have free play gently tighten the two out screws until the saddle is just tight. You may need to experiment to make sure that both screws are having an effect and it is not just tight at one end. Then gently tighten the middle screw until you have free movement without excessive play.
If the saddle locks up gently loosen the two outer screws until it is free and proceed as above.
You should not need more than finger pressure on a standard length Allen key for the above adjustments.
Best regards
Roger