smontanaro 

I'm back from Michigan and starting to catch up on email. I spent a bit of time with the Univega this afternoon. As far as I can tell, the "ports" on the left and right side of the binder assembly are identical. Switching left-to-right won't improve things by itself. The 26.8 seatpost is a perfect fit (nice parallel slot). It doesn't slip when I can get the bolt & nut snugged up. I searched through my box of odd small wrenches and found one to modify. Aside from too much underbiking which wrecked a nice tubular, I've solved the problems with the Univega


Seatpost slot detail

Nut detail

Modified "wrench"