Exhaust rocker shaft

[Sakura]

Going over my RGS, which I recently bought back, taking out previous owners stupidity, I found the exhaust rocker shaft snapped where the drive side oil hole is. Fracture looks like the shaft may have been over hardened. However, the Eddy Dow manifold has 3/8" spanner sizes, whereas the originals are 1/4". This, of course, allows a ham fisted, ignorant numpty to apply a lot more pressure than BSA intended in order to cure an oil leak. Not a problem, I've got a well known dealer friend who let me check his s/h stock and pick the best one (0.001" u/s, which I imagine is standard)  FOC.  Result!
Have any of you come across a broken shaft before?

[Swarfcut]

 Yes, I have one, fracture is at the Acorn Nut end, (timing side). Break is the same, at the oilway drilling. This time it's the inlet shaft, found when dismantling the rocker box to check a used purchase. Looks an original BSA part.

 Swarfy.

[Sakura]

Yes, same here, timing side. Interesting! Of course my engine is a late 62. I wonder if there were a batch overhardened. Probably most have been rectified a long time ago.