Product review (5 stars): This is the design these products should have originally shipped with...
This was the kit that fixed my Sears / Kenmore upper rack unit.  My experience with the roller breakage is similar to what others here have described.  Rather than replacing with the same original defunct design, I was fortunate to find this new, and improved designed replacement kit from Maytag.  For reference my Kenmore is model 66513293K114.  As others have indicated the provided instruction sheet is not all that good.  After watching a short YouTube video titled "Whirlpool, Kenmore, KitchenAid - Dishwasher Replacement Rack Adjuster Kit # W10712394 V-rail", it was a breeze to remove the old setup and install the new kit.  Best of luck replacing yours! https://www.youtube.com/watch?v=otUn8eoceBw