I noticed that there was water in the bottom of the dishwasher tub. Eventually it became clear that it was clean supply water, rather than dirty water that had failed to drain out. Web searching led me to this part. It was quite easy to change it out, thanks to the very helpful video. I did have a small leak after and had to change where I had seated the hose clamp, which was easy, but a reminder that it's important to check for leaks before closing everything up again.