That's impressive. How worn is the rest of the vise? That is a pretty tedious repair re cutting the groove and then reinstalling a handle. Not too difficult if you have a med sized lathe and welder. I had to repair a parker 955 screw that was not quite that bad. Might be able to find someone locally just to weld it up and re cut the groove then you can make your own handle fairly easily, but at the price for replacement parts vs time searching it could be a wash.
Kevin, how are you cutting the groove? Do you have a 4th axis on your machine? As always impressed, especially considering you don't have a lathe.