I tried my idea of a bicycle pump for pressure, but when I found it, my daughter had apparently broken the needle off. Considered walking over to the construction guys doing repair on the apartment complex, and might have to do that later, too. Considered oil, but that would just make them slippery to try to pull apart. :-\
My large cups were easy to get apart. I can't even get the plastic off of the stuck ones, though. Too bad the NG pump doesn't reverse.