Why won't water pump out of the bottom of my GSD500 tub?

First, check if this is a drain problem by verifying that your kitchen sink drains well—you may need a plumber. If the dishwasher drains into a disposer, run the disposer to clear it and make sure it's not clogged. Also check the air gap, if you have one, to see if it's plugged. Some water around the outlet on the tub bottom at the back is normal and keeps the water seal lubricated.