There is small plastic clip that has worn out. (it isn't that good of a design using plastic for a wear surface)
You need a new dispenser. I just replaced mine. It's not that hard.
Order the new part, remove the star pattern small screws on the inner part of the door. This will allow the outside door panel to come off. Remove the electrical connectors (2 on my style) on the dispenser. Gently bend and push the metal clips (sort of) that hold the soap dispenser in place. Lubricate the new part's oring for easy installation. Use something like dish soap or rinse agent. Push the new dispenser into place until all the metal clips engage on the dispenser. Put door back on and install screws.
Hope that helps.
Andy, November 2007