The dishwasher is original to the house and is getting on 10 years now. It's a pretty basic model and nothing very fancy. Lately it started having problems where it wasn't filling with water. Figured the dishwasher was finally starting to give up the ghost and it was time to start shopping for a new one.
Fortunately, I had remembered someone I follow on Google+ describing a similar problem and that the solution was a stuck flood float. Giving it a tap got it working again a few times, but then the dishwasher started doing the same thing again.
This time I decided to dig a little deeper. A single screw holds the cover of the flood float on so it wasn't hard to remove.
Warning: If your dishwasher is as old as mine, this operation is not for the squeamish.
Underneath the cover is the actual flood float, which is a similarly shaped plastic cup that sits on top of a plastic pin that does the actual switch/valve actuating. Between the cover and float was years and years of built up gunky moldy goo that used to be food debris. Lifted the float off and inside there was even more built up gunky moldy goo. Well, no wonder the float was getting stuck.
I didn't think to get any pictures, but it's probably better that way.
After clearing out all the goo and giving things a bit of a rinse, I put all the pieces back together and the dishwasher went back to work like it was supposed to.
If your dishwasher has one of these, you might want to grab a screwdriver and see if it needs clearing out. Might save you a bit of trouble down the road.