I broke one a few years ago and the arm still came out with the pump, it was just snapped at the pivot point but not completely broken off.

I have also pulled an A12 down and the fuel pump lobe on the cam was warn down to be completely round in the centre of the lobe where the pumps lever rests on it.
This engine ran an electric pump and just had the mechanical one left in place. All I could think was maybe the pump slowly siezed from being dry and this extra force placed on the lobe slowly wore it down.