Product review (2 stars): Save money, use zip ties
There is an additional write up for this quick procedure, but I have to endorse it. Works like a charm and saves you 30 bucks. Remove rack. Secure a 4 inch zip tie on the front and back of the rollers... inline with the racks (ie. front and back, not top and bottom. Don't pull them too tight, but definitely make the roller snug. It does not have to actually roll. The track is stainless and the rack will move smoothly whether the rollers move or not. Clip the ends and re-install. Three out of four of my rollers had snapped pins. It seems wasteful to purchase the entire assembly because the plastic pins become heat-brittle and fail. I would not suggest using glue or epoxy due to repeated exposure to heat and water. It will simply fail again. Cheers!

UPDATE: As expected with this method, the zip ties do eventually fail and must be replaced. Just keep an eye out from time to time and replace as necessary. I still think this is the quickest, most inexpensive technique for solving a definite design weakness in an otherwise good KitchenAid dishwasher.