Took my 14 classic out of the case this am and this piece was spun around and about to fall off. I took it and tried to see what was wrong and I知 actually not sure. I see how it goes back on by the detent riding in the groove in the bolt. I can see there is two balls in the hole but there痴 not really a positive lock up when the detent goes in the groove. Should there be a spring or another ball I知 missing and what is this part called?