This pic is of the seatpost bolt nut on my Univega Super Speciale. I've never been really successful holding it in place while snugging up the bolt. I've tried screwdrivers, nickels, chainring bolt wrenches. Nothing seems to work well. Of course, my seatpost slipped while out in the "wilds" of Michigan just now (a bit south of South Haven). I've done what I can to tighten it up, but suspect it will slip again (yes, I have the proper size seatpost).

Is there a wrench for this beastie? If not, I think something like JB Weld will hold it in place. If I was going to get the frame painted, I'd probably just have it brazed in place.