GE Nautilus draining problem

After completing wash/rinse cycle a couple inches of water remains in machine. Have removed the filter and sump cover and cleaned out debris, ran cleaner through machine, but still not pumping out all the water. After reading other posts on forum suggesting the piston/nut could need replaced I looked at parts diagram for Nautilus model GSD2200G02CC but didn’t find a piston/nut for this model #. Any suggestions on how to proceed?