Cratecruncher

I did try a piece of double sided masking tape trimmed down slightly smaller than the clamp itself. It didn't improve things. What gets me is that this is a standard Campagnolo bracket used on countless bicycles for well over a decade. It surprises me that I am the only person that has ever had this situation come up? I saw a frame recently that had a small bar or pin brazed onto the underside of the downtube to prevent the bracket from slipping. It was painted same as the frame so assume it was original.

Next thing I will try is removing any wax residue and apply a drop of Weldwood contact adhesive. That stuff is pretty sticky but not permanent and won't harm paint.