This was a known issue with the originally fitted pins which only had an M10 thread into the wheel, clearly not up to the V-Twins Torque delivery! (although this is the worst I've heard of) The factory I believe changed to M12 and finally M14 threads in the course of production. Fingers crossed I could source some of the upgraded parts (also replacing the rock-hard, aged rubbers at the same time!) and that the wheel itself could be rescued.
Well, I managed to get the wheel repaired at a local shop run by a long retired ex speedway racer/engineer. Mainly busy with classic and vintage car stuff.. Workshop a collection of old lathes, milling machines, swarf and shelves upon shelves of well thumbed manuals and data books. He doesn't advertise and nothing outside his unit to indicate... took me two attempts to find him! I think he only took pity on me because he likes bikes! Says he prefers to stay hidden as he's got more than enough work to do and 'old stuff' never takes less time than customer thinks it should! Anyway after 90 mins of charged work I had a wheel back with broken bits extracted and M14 THREADS IN PLACE! Very reasonable since he had to extract the sheared pins and then make a tool to centre the drilling and tapping. One thread was touch and go due to previous damage but I managed to screw in a new M14 'test pin' to all threads before taking the wheel home and packing it off to the powder coaters.