On 17 Sep 2013 02:51:17 GMT, Puckdropper
It might be possible to hold things together with a metal band on either
side of the screw hole. A piece of square stock measuring close to 7/8"
should do it, perhaps with a little filing.

Could be poor design as Mike mentioned or the problem might be
something else ~ metal fatigue.

Had an Emmert vise passed down to me from my father. It fell apart on
me section by section. Had the same thing happen with an older drill
press too. Some of the older tools are pretty good. Some just wear out
over the years.