Paul,
Congratulations on getting the Youngstown Dishwasher back to Ogden. I am pleased to hear that it is in pretty good shape.
Regarding the Water Pump - I think I would start soaking it in Limeaway for a few days to see if that will start to loosen the impeller and the green gunk. Other than that, I am not sure what to suggest.
Interesting that the cabinet says "Electric Sink" even though this is a stand-alone unit.
The term "Electric Sink" - I do not believe that it was a patented term. Various sink/dishwasher combo manufactures used the term "Electric Sink", at least from what I see in my vintage magazine ads. However, a 1927 Walker ad called their unit a "Super-Sink." The 1930 Conover brochure called their unit an "Electric Dishwasher Sink." Besides Youngstown, both Westinghouse and General Electric used the term "Electric Sink". Both Crosley and American Kitchens referred to their models as "Dishwasher-Sink Combination" or "Combination Dishwasher-Sink". Apex used "Dish-a-Matic Sink". KitchenAid uses the terms "Dishwasher-Sink Combination" or "Dishwasher installed in a cabinet-sink combination".
The switch you are showing, is definitely the control for the Garbage Disposal.
Good luck with the rest of the restoration.
Mike