OK after our first trip with the 2503S the fresh water tank wouldn't drain. Husband and I both looked at the valve and it is riveted in. Well while DH was away today I went out with a flexible straw and a piece of the tube from a soap pump. Laid on my back in the driveway and started blowing air through the drain valve. Could hear it bubbling in the fresh water tank after blowing about five times it started to drain.
You never know what a determined woman will come up with to fix a problem.
Know that there is something in the fresh water tank that blocked the drain. In case it happens again I plan to add a piece of longer flexible tubing to our toolkit.
The men can laugh all they want about how I fixed this ( for now).