I snapped some pictures of the underside of the dishwasher since I had it disconnected and upside down. It is pretty ingenious how the pump housing is made so that it serves as two pumps depending on which direction the motor is turning. The dishwasher seems to be designed to use as few parts as possible, and for the most part, there isn’t much to go wrong with it. There is a diaphragm that seals the drain outlet when pressurized by recirc water, and moves out of the way when in drain mode. This diaphragm was torn, so water diverted into the drain chamber just reentered the recirc chamber.
