Replaced the seal and push nut to stop the leak. I was able to clean the rust off of the piston and solenoid so that it would open and close the drain flap properly. It hadn't been washing well, I think, because the drain flap wasn't closing and some of the water was draining out as it went through the wash cycle. After fixing the leak and cleaning the solenoid, the drain flap worked properly again and the dishwasher is now washing well again. The video was very helpful, but it was pretty easy to get to these parts on my GE Nautalis without pulling the whole dishwasher out. I just removed the bottom face plate.