Product review (5 stars): A quick and effective fix.
My Kenmore washer's agitator was not working as it should.  I found a video online describing the location and replacement of the washer dogs. Popping off the hub cover at the top of the agitator, I could see shards of plastic where one of the dogs inside had broken. I purchased these and after a 10 minute job, my washer was working again!

One suggestion for people wanting to do this on their own - make sure you have at least a 12 inch extension for you socket wrench. The bolt holding the agitator onto the shaft way down there.