Same problem twice within a year of fitting this bath, and water in the tub on both occasions.. somehow the scew works tself too far into the actual plug, then the round knob does nothing about lifting the plug up...best solution is to empty the bath with a bucket to releive the pressure, then suction the plug up whilst turning knob and ''voila'' it come up no prob and you can then glue the screw in the right position with araldite or something similar!!!