Locking Bolt

I've seen this part described as a both a locking bolt and a takedown lever. Whatever you call it, it's loose on my 1915 artillery. I shot it today and noticed that it would flip down repeatedly after I fired a few rounds. I had visions of the the side plate falling off, but it never did. On some exploded drawings I've seen a "locking bolt spring," but not on others. My gun doesn't seem to have spring. What's the collective wisdom on this problem? Thanks.


Don