This is a very interesting rifle. I suppose, that since it is a back action lock, it has done what these locks do best, break the lock mortise. This is usually either because the front of the lock doesn't contact the snail, or lock bolt has been left loose, or broke, causing the lock to buck up, and destroy the mortise. They also are pretty good at letting their incredibly long mainspring get loose, and blow out the lock mortise.
I would love to see more of this gun, It has very interesting furniture, and lines.
Hungry Horse