Hi Karl,
Man, you got sharp eyes!
I believe both curves you are seeing are part of the taper of the yoke forging. I have added this observation to my list of things to check once the parts are out of the car.
Mike B. has reinforced your original observation about the lack of ridge in the factory weld area. If someone ground this weld ridge down for appearance, before or after I bought the arms, it may have been enough to cause the failure. Another thing to thoroughly check after the parts are out.
Surgery #2 was not as bad as #1, but the pain & swelling have returned full force today
