my ice maker is making ice, but extra water is spilling over into tub creating a large block of ice. the "tray" fills with water, but some (i assume) is overfilling, and dribbles into ice bin, then freezes into one large block of ice. nothing "extra" in tray (no ice, blockage, etc), all eight cubes come out. once they come out, when water fills tray, more water comes out than tray can hold. so water dribbles over into tub. tried turning adjustment screw, but didnt seem to work(maybe i didnt do it right). seems to fill longer than it used to (longer fill time- at least it seems that way). any ideas.