I fixed the problem by following the video and replacing the chopper.
My Maytag MDB8959SBS3 Dishwasher originally used ball bearings in the upper dish rack assembly. Over time the plastic which holds the ball bearings hardened and then broke and the ball bearings and plastic pieces dropped inside the dishwasher. I was able to retrieve some of the ball bearings and plastic pieces but I didn't think I got all of them. I replaced the upper dish rack slides but about a week later the dishwasher developed a humming noise.
I searched the internet for videos on how to clean the filter for my dishwasher when I came across this video for replacing the chopper. I read thru some of the stories and thought that the humming noise might be the chopper so I took a chance thinking that the chopper was either defective or had plastic and ball bearings covering it. It was no surprise that the chopper was clogged with plastic pieces and bearings. I don't know if the chopper was defective but I replaced it anyway since I had already taken it out.
Works perfect now. Thanks for the instructional video. There were a few differences from the Whirlpool to the Maytag but it was close enough to guide me thru my repair. Major difference was:
1. No screw on the Maytag to loosen back pipe. Clips hold the pipe to the back of the dishwasher
2. Maytag had a filter which snaps on around the bottom which the Whirlpool in the video did not
Otherwise, everything from the video was the same.
I used the same tools as displayed in the video. The use of the 11/16 wrench was extremely helpful. I would have wasted hours trying to get the chopper back in. It was a breeze with the wrench.
Again Thanks for taking the time to create and publish the instructional video.