Why is it that after running the dishwasher on any of the cycles, there is water sitting around the bottom of the tub. This water keeps the unit from drying the dishes completely or at all. If the "drain/cancel" button is pushed, the remaining water is removed. Sears has said it is an issue with the plumbing and not the unit.... Why is it that I can get the unit to drain if I push the button? This units model number is 66513573K700