Went to on line video and followed it. The old gasket came right out and the new one fit right in. Started at the top middle and worked the gasket in on both sides to make sure it was evenly spaced.
have had same problem many times under extended warranty pump was changed by factory and installed wrong it was jammed in so take out there is a realest lever and twist clockwise install buy twisting counter clockwize
replacing the sensor was simple, just unplug and turn it out, but didn't solve the problem, it's a float sensor that doesn't show up on the tech sheet in the dishwasher or anywhere in troubleshooting on the internet I could find.
dishwasher not emptying tub, dirty dishes when the dishwasher said the cycle was done
easy repair, but the check valve wasn't the problem, it was the float switch that isn't on the tech sheet in the dishwasher or mentioned as a possible culprit anywhere I could find on the internet