Corners of the top rack generally should not be used for narrow objects if the water from the bottom wash arm is blocked, although my 2 18s have the larger wash arm and china guard that came out with the 19 series and I have not noticed much trouble. The thing with the newer KA machines is that even if nothing was blocking the water from below, tall glasses in the corners of the top rack were not getting cleaned because the spray from the bottom wash arm was not reaching all the way up into them. This is a pretty damn sad legacy for a brand that once ran an ad in Life Magazine showing a KD2P (top load portable with big blue wash arm) with the lid open and this great upward spray of water. The text read that if you could run this KitchenAid dishwasher with the top open, which you could not, the water would shoot 10 feet into the air and the same motor, pump and wash arm were in all KitchenAid dishwashers. It's even sadder than the switch from fan forced drying to just sitting there drying. Another ad campaign KitchenAid used showed a Rubbermaid dish drainer stacked full sitting over a surface unit on an electric range. The text said that this was the way most other dishwashers dried, but KitchenAid had fan forced drying that was gentle on dishes. You should have heard long time KA dealers at the meeting where the models with no dry fan were introduced. They wanted to know what they were going to tell customers because KA owners coming in for a replacement machine would have to be told of the change and the dry system had been one way of moving customers up to KA from other brands.