In my experience with the innards of 73 Winchester. If the proper parts are inside which I'm assuming are.
If someone possibly forces a round through a cycle, for whatever reason, a toggle could be bent, or the connecting pin on the toggle link could be bent.
Usually as they wear, they still operate, just sloppily.
Thinking about it being forced sideways, someone suggested possibly the wrong toggle, maybe a 76 toggle link being longer in a 73, forcing it toward the side plate.