I hoped the problem was just something jammed in the chopper, but it turned out that I needed a new circulation motor (it also comes with a new impeller). The Appliance Parts Pro video about this repair was very clear, and I was convinced I could do the job myself. I ordered the part and it showed up the next day (wow! I'm just two states away from the warehouse, but still, that's fantastic for less than $7 in shipping for this part). The repair was just as easy as the video depicted--it took less than 60 minutes from start to finish. An appliance repair shop quoted me $150 labor, and the part would have been more expensive, too.