Ordered the right replacement from this site. That's a little tricky, as there are several that look similar. Check model numbers on the washers carefully. It helped to call a local parts store and they give part numbers to match the dishwasher model, that helped confirm I had the right one. Their price was about $103. The price on this site with shipping was $86. And it came in the mail the next day.
Replacement went pretty easily. For our model of washer (Maytag MDB4709AWW3), you actually unscrew the 8 screws nearer the bottom - - need a small torx screwdriver - - and then it's the front panel of washer that comes off, not the inside panel.
Then you need a small hex socket, and nutdriver if possible, to unscrew the 6 machine screws for the rectangular retaining piece. Pay better attention than I did to how the electrical wire relates to that retaining piece. One trick is that the part that came had stuck to its connector an extra connector for the wire. Probably, that comes off, since the same part is also on the end of the wire that remains on your dishwasher. The two don't mate with each other!
Reassembly was pretty easy. A second person to help hold the front panel on while you replace the torx screws might be helpful. So far after one or two runs, the dispenser is working.