The cat brought in a rat which ate holes in the sump inlet.

First, I took off all the pipe clamps and retaining brackets. Then, I pried it out of there. One of the tabs holding one of the other bits to the body got busted, but it didn't matter, as it is held on very well just by the pipe clamp connection. I stuck the new one in and re-attached all the hoses. The GIANT complication was that a new floor had been installed over the old floor, right up against the kick plate- so in order to remove the dishwasher, I had to slice open the counter, as the new floor prevented sliding it out. To prevent the problem recurring, I spray painted over the sump inlet to make it taste worse. This is the downside of a cat door.