Flightmaster Cal. 911 Rattling Sound

This is my very first post here. I can believe how I have avoided this place for so long. I have been a member for an hour and already found parts I needed on the sales forums!

I just jot a lovely Flightmaster. It's the first one I have ever seen in person. The watch has a metallic rattle if i shake it. Almost as it there is a rotor inside. Movement runs well. Nothing seems to move from the dial side. I have opened the case and everything looks good. Nothing is obviously loose.

I suspect it might be the inner bezel. Is this the norm for these or should i fully disassemble it to investigate further?n I know if this was a modern Omega it would signal a major problem but I can imagine this being just the way it is on these. Any insight would be appreciated!