After very closely examining the bowl, I think its possible there is a leak between the fuel inlet (the cylinder the bronze filter sits in) and the bowl, circumventing the inlet valve. There is only a couple millimeters of material there and it wouldnt take much to cause a leak through, even under only 5-6 pounds pressure. And, it could be right in the area I filed on in that slot
Is the bowl made of aluminum alloy, with maybe zinc? Thats what can corrode. I have a little gray corrosion in a couple spots here and there.
Seen the 71 outboards "new" for as little as about $399. May eventually have to go that route, but hopefully not too soon.
I have other things I would rather be spending my money on, like a 5 speed and a digital classic am-fm radio!
You know. Important things!!