Is the bolt portion stripped, or the plateit passes through? If just the bolt, you can replace that locally from a hardware or builders supply. If the carriage itself is boogered, then you may be able to clean it up with a thread tap of the matching diameter and pitch.
I guess I'll just have to look into that then, I wasn't aware that Beseler changed any major parts like that. Beseler claims that all modern parts fit their older machines.
Just looked on Calumet for refurb kits, and they show it as a replacement part for all 23C machines.