What keeps the Opinel open if you remove the lock? The one I had was lethal without the lock, would close on you if you so much as sneezed, whether or not you were cutting at the time!
Interestingly Opinel started in 1890. The Virobloc mechanism was invented a lot later by Marcel Opinel in 1955
seemed to work fine without the lock back then I would imagine the wood slot was a tighter fit as the opinel 'knock' has always been needed to open them
I gave my handle a soak and it swelled the wood for a much better fit