Can that square shank be drilled and tapped for a 1/4" or 5/16" thread? Then screw a tall bolt into it and epoxy a ball bearing onto the top of the assembly for the bolt to slide through.
Jerry
Maybe a quarter inch hole, Jerry. Anything larger than that might be on the edge. That is either where the wear happened or it is where sloppy mfg work produced a too-small square at the very top.
