My '75 Mk III had the suspect Portugese ball bearing in it; manufactured in 2/75.
I suspect that when Norton found out about the bad bearing they had greater troubles keeping afloat; the only motorcycle company that I can think of that went out of business faster than Norton was Buell. I am also sure that the bad bearing looked good on "paper", good enough anyway. Who, back then, could have predicted the effect of owners slamming gears, not changing gearbox oil or letting the gearbox slowly fill with water? (my gearbox had almost a 1/2 pint of water in it after sitting for 27 years and 6300 miles in the PO's dining room....go figure).
RS