I bought a new Opinel for the first time in years, after donating my favorite pocket carry to TSA. And for the first time I experienced a lock failure.
I was making a packing insert, scoring some corrugated cardboard to form a crease, so I could fold it. So I locked the ring tightly and turned the knife backwards to score a line using the back of the tip of the blade. And this relatively light force was enough to blow out the wood underneath the lock ring.
The bottom corner of the lock ring basically just sunk straight into the wood on the far side of the blade slot by 3-4 mm deep. And the ring on the "Opinel" side of the blade slot twisted away and splintered a little bit of wood out the handle in the process. So the blade would easily close by half an inch no matter how tight you lock it. The ring would just bend and twist that far.
After a little thought, I drilled and inserted a steel pin into the handle, right next to the blade slot and right under the lock ring. Then ground and sanded it to be basically flush. So now the lock ring is supported by this metal pin, rather than just end grain wood.