I stood by the dishwasher as it went through the cycles and noted the noise only happened during the drain processes.
To make this repair you have to take the dishwasher completely out from under the counter. (NOTE: print the schematic to help guide you to the location of the part and connections.) The pump is not accessible from underneath. I laid the dishwasher on its side. I recommend disconnecting the copper fill tubing before laying the machine over (I did not and crimped it). The pump is held on by two screws and two hose clamps. It removes easily and goes on easily. When you put the dishwasher in place, pour 4Q of water in the bottom as the first cycle is a drain cycle and needs water. On the old pump I noted that the impeller would not turn freely which was the cause of the hum. It now runs as quietly as it did when new.
I also found the repair guide in the frame of the dishwasher AFTER I was done. It illustrates step by step how to test each cycle to diagnose any problems. Look for this before you guess at repairs. I do most of my own repairs and this was my first dishwasher. All of the parts look easy to replace on this model.