Actually, I just recalled something about the screw thread systems that Victa have used.
The early ones, through the Model 5, used all BSW/BSF threads.
But from then on, they're nearly all UNC threads, with the sole exceptions of the crankshaft end threads - those remained 1/2" BSF.
Victa even had/have special AF/SAE hex nuts made with that thread in them, so that AF wrenches would fit every fastener on the mower.
So while the BSW insert kit will work [same 20tpi pitch, but slightly different thread form], the correct one is 1/4"-20tpi UNC thread.
