Thanks for the support, as always, to everyone! The Stovebolt reigns supreme!
I played with the pump some more at home yesterday afternoon, enough to figure out that:
A, I think the Barton manuals really mean it when they say "SAE 20 weight oil" only in the gear case. We used 30, since that's what we had on hand, and actually, 20-weight seems a little hard to find. Well, turns out the friction clutch is sluggish to spin the impeller shaft fast enough to lock in the positive clutch, and I think the heavier weight oil is the culprit. Time for more testing.
B. found a crack in the back side of my booster tank shut-off valve. Have to remove, repair, and replace. No biggie.
c. Need to repack the booster reel packing gland. Water went EVERYWHERE!
Still and all, quite fun. Have a 12 gallon-per-minute booster nozzle. With the 500 gallon tank . . . let's see . . . 12 into 50, about 4 . . . that's 40 minutes of play time showing kids what it's like to spray a "real" fire hose. Or, a lot less with an inch-and-a-half hose & nozzle. Awesome.
BTW Don, found the copies of the manuals for you - where should I send it?
More to come,
-Michael