Started working on the left fuel tank. The inboard end of the left wing slid off the wing cradle a long time ago. It put a slight dent in the most inboard part of the leading edge, from where the tank rib is to the edge. I checked immediately and discovered a new leak, but waited till now to diagnose and resolve it.
It turned out to be simple. The dent pushed one of the rib tangs out very slightly, but enough to tear the proseal loose from the skin and cause a leak. The leak wsa confined to the immediate vicinity of this rib tang.
This likely means that the inside is not sealed super well in the area, although I'm not sure how that could be, I did use quite a bit of proseal. The dent doesn't go inboard from there.
To fix it, I sanded the area and cleaned it up with lacquer thinner. Then mixed up some proseal. Put some lacquer thinner in the bottom of the jar to thin it, and applied this slurry to the leak. Applied a little vaccuum and worked it around for while to try and feed some of the proseal into and through the leaky area. Then I applied gob of unthinned proseal to the area.
This definitely fixed the air leak, I hope it fixes the problem for good.
Moved the fuselage to the airport. Should be jumping for joy, but it was almost a disaster. I'll explain more when I'm not in shock. The plane arrived intact, that's what matters.