Just FYI, people might sound slightly puzzled because...
Failure of the plastic gear plugs is extremely common. So common that I keep a couple sets on the shelf at home for the next time mine fail.
And failure of the metal gear and scissors is extremely rare. As in, my family has put maybe 300,000 miles on MN12s, and I have never seen one fail.
Just saying, before anyone goes drilling out rivets and messing with spring-loaded devices, maybe ask if he's sure that the $6 plastic pieces are good.