I haven't concluded that the pump itself isn't working yet since I don't know if the pickup is currently above the bilge waterline with the way the boat is leveled on the jack stands. But it's good to know that I can do a rebuild kit rather than replacement if it is the pump.
In the head area under the teak slat floor risers there's an approximately 2'x2' a 1" deep shower pan canted downward toward the stern, which just has a circular area of drilled holes in the fiberglass at the lowest point for the gray water to drain directly into the bilge. It looks like the pipe I mentioned forward of the mast goes directly to that area and is canted downward toward the stern too.
I don't know for sure that there's not a deeper well (sump) under that pan. But based on the lowest point of the bilge that I can see and the relative location of the shower pan, I doubt it.
Where is the manual bilge pump pickup placed in "your" boat?