The adjusting screw should have a spring, tiny washer, and o-ring. If you are not careful when removing the screw, one or all of those parts can drop off and hide forever from you. Also, if you are missing one or more of them, check inside the hole for the screw; the o-ring especially can easily get lodged down inside there and if you do not notice it being missing, then when you insert the screw back in the hole and screw it down, the o-ring gets mangles all to pieces.