I'm pretty sure you weren't supposed to mess with that screw. Tigthen it up. bench bleed the master cylinder, install it, and then bleed all your lines, starting with the drivers front, passenger rear, passenger front, and drivers rear in that order. Bleed with a friend to make sure all the fluid is out. its also nice to get a fluid dye, like blue, so you can tell when all the old fluid is out and new fluid is in