I repair and resell used dishwashers as a retirement hobby. After having examined many dishwashers that were replaced because they wouldn't drain, the largest percentage of them were simply because of a clogged drain hose or pump strainer. Too many people seem to think that the dishwasher is first cousin to a garbage disposal. It is not. Even if the instructions state that you do not need to pre-rinse dishes, you should pre-rinse them anyway. The macerators in the dishwashers(the thing that grinds up the food particles, slightly similar to the one in a disposal) are designed to grind up small, soft bits of food, not leftover steak scraps, popsicle sticks, wire bag twist ties (or even plastic ones), paper and plastic jar lables, etc. Yes, I have found all this and more in the pumps). This stuff will clog or possibly destroy the pump/macerator assembly, resulting in a costly repair or replacement of the dishwasher. Sometimes, if enough garbage makes it past the pump and is drained, it begins to collect in the drain hose, and will slowly build up over time to the point where, lo and behold, it will no longer drain. easy fix for that is to first remove the drain hose end from the nipple it's connected to on the sink or disposal, put the end in a bucket, then fill and drain the dishwasher to see if a garbage clog will simply blow out. If that doesn't work, but you see a small dribble of water, you may have to pull the dishwasher out and remove the hose from it to clean it out. Don't forget that there's still water in the unit, so put a drain pan under it before removing the hose, or even better, if you have the unit completely out of it's hole, just tilt it onto it's back before pulling the hose. do not tilt it onto it's side or front, or you'll have the water running out, or into the door cavity, possibly doing damage to the controls.