The G103 spigot problem was due to faulty materials
in the manufacture of the spigot...

I think it might have been a bit more complicated than that. Back when
the Grob Spigot-Fixin' team was on their US Grand Tour, I saw the old
and new spigots side by side. I don't remember the exact details of
the design beyond that it was a plate of steel with a cylindrical
protrusion emerging from one edge. But I do remember thinking that the
old style was somewhat casual in its execution, while the new looked
much more robust, with much more of the filleting you'd want for good
fatigue resistance.