WFR.RR,
Thanks for the tips.
EdInMass had contacted me and explained about the valve (can I call it a "power valve?") which is operated by the black lever&rod system. He told me that the valve often gets clogged with debris, and this causes lean running. Sure enough, there was lots of dirt and rust clogging it when I removed it.
I cleaned it up, re-installed it, did a little cleaning to the inner castings "while I was in there", dressed and re-set the needle tip, tested and polished the float and counterweights, did a few other sundry things o make it "tight" and of course tested it wet. It has probably arrived "home" by now.
Jeff Dreibus