My first thought with all these repeated flats is that your rim strip is torn, shifted off where it should be, or missing. That can cause a lot of problems. It looks like a layer of tape running along the rim with a hole in it for the valve stem.
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Bikes: 1996 Eddy Merckx Titanium EX, 1989/90 Colnago Super(issimo?) Piu(?), 1990 Concorde Aquila(hit by car while riding), others in build queue "when I get the time"