Valve Body Gasket

Disconnect the dishwasher power supply and water connector.Then disconnect the drain hose.Take off the hose from the pump and on the plastic valve is the black valve flapper.Mine was swollen twice the size of the new one.Replace with the new one.You have to pull the dishwasher out and turn it over to do this.
The check valve was totally worn out.You must turn the dishwasher back to it's in use position and open up the door.Inside the lower rear wall is a plastic cover with 4 screws remove these and the cover.Then unscrew the piston and nut assembly and remove the check valve.Simply replace with the new parts and reinstall the cover.
I replaced the gasket before I reinstalled the check valve even though it looked ok.To do this you need to turn the dishwasher over again and remove the 4 screws dolding the resevoir the check vave is in.Replace the old gasket with the new one and reinstall the new gasket.Do this after removing the old check valve and before intalling the new one.
On the bottom inside the dishwasher I noticed the large white gasket on the floor was falling apart so I replaced that also.I'm glad I did because below this assembly there is a reusable plastic filter that was totally plugged that I cleaned and reinstalled before relacing the filter gasket assembly.To do this you must remove the plastic water jet.With a screw driver there are 2 plastic tabs that must be carefully pulled out so you can pull out the water jet.Remove the 2 screws and plastic cover on top off the gasket assembly.Retain the 2 screws but you will not need the cover it is part of the new gasket assembly.There are two clips you need to carefully pry off.Then lift out the old gasket assembly and replace with the new one.Reinstall the 2 screws that held the old cover before and If reinstall the old clips if not damaged.You can purchase new ones but usually not needed.Then gently snap the water jet in place.
Put the dishwasher back under the counter and reconnect the power,water line and drain hose.

Changed check valve and valve flapper. Had to pull dishwasher out of cabinet to get to the backside. Removed check valve and replaced valve from inside dishwasher ( all the way at the back, large nut holds in)but had to remove lower assembly from rear in order to change out the gasket. Removed large black flexible tube and replaced flapper valve. Just be carefull sliding hose back over section containing flapper valve. Fairly easy switch out. Took care of problem.

First I replaced the flapper valve of of off the water pump. That worked for a couple of days, then the standing water was back. After more research at your site I ran across other person who had the same problem and they ended up replacing the piston and valve assembly. After pulling the dishwasher out I was able to find where these parts were located. The piston's rubber part was half gone. I replaced it and the gasket and another flapper valve. This model has two flapper valves. One difficulty was that you have to replace the screen inside the dishwasher before you replace the housing that the piston fits in. Your site and other folks contributing their stories helphed me to solve our problem. The dishwasher works like new now. Thanks. Ralph Naddeo.

Went to repair parts on troubleshooting and found check valve assembly to be most common problem. Went to parts diagram to locate assembly and found it somewhat confusing as to exact location. Ordered part(s) on percentage as the problem. Received part next day (great)! Pulled dishwasher out and found I did NOT need to do so to replace check valve which is replaced without having to remove dishwasher. The gasket replacement was not necessary as it seals sump area from bottom of dishwasher and not the valve as it appears on the parts diagram. It took about 2 minutes to replace valve itself and it was the cause of the problem.

After reading about this problem on an appliance repair forum, I learned that it is usually caused by a faulty piston valve. The valve is located under the rear screen filter and can be removed with your fingers. The parts arrived very quickly and we saved $$$ by not having to pay for a service tech visit and "mark-up" on the replacement parts.