I wish I could say I've only heard about this...
My daddy told me the best way to learn something is to make a few mistakes, and focus on not repeating them. Oh, and be ready to do it over. I only made this particular error once, and I hope I can prevent someone else from repeating it.
The error can be made easily from the top of the engine - just push the Dizzy in wrong. The fix is enormous - you have to pull the pan off (mostly best done by pulling the entire engine) to get at the oil pump.
Once you do that you might as well send the pump to Gordon Raymond, who will rebuild you the absolutely best oil pump in all of Alfadom!
It is but one of the many things I have "learned" about Alfas.