Replaced the piston assembly at rear of tub bottom. Plunger gasket had eroded and would not seal. Removal of two hex screws and drain cover allowed removal of defective piston assembly (used pliers handles to unscrew assembly). New assembly was easy to screw in, then replaced cover and screws. Only extra step was to unclip heater coil from clip to gain access to screws more easily. Very easy repair, and fixed the problem.