I changed the Subject line...
I bought an oil-less compressor from HarborFreight (pan style, 100psi) for $60 on sale. With a 50ft hose and used regulator for another $75, I have a hookah system for cleaning the bottom, unfouling the prop, and changing zincs, as well as compressed air for lots of other things. I run it off of my 1800W 24-110AC inverter.
My screws holding the center stem to the base are not hex head. They are flat screws. See my photo of the center stem. That rattle gun sounds like a winner. I don't have any dive bottles (yet), so that's a no-go for today. I'm off to the Ferretería to purchase some better penetrating oil, a torch of some kind and a replacement bit for my impact driver and give this another go.