primer injector in 15HP 93 Mercury & ball bearing

I'm digging into my 2 cycle 1993 Mercury 15HP for the first time to rebuild the carburetor. For the most part, it has seemed straight forward. However, I was following a youtube video where somebody was breaking down a WMC 53 and they showed a little ball bearing in the primer injector setup. I have a WMC 39 I believe. When I opened mine up, no ball. My rebuild kit has one and it fits in there and appears to not be detrimental. However, I was a bit puzzled as to whether this carb should have one or not. TO make things a bit more confusing, I can hear a little rattle inside the piece but can't' see anything AND I just noticed a weird thing today as I put it back together. One of the holes on the outside of the piece seems to have "what might appear to be" a little metal bearing stuck in it. I really have no idea IF/OR/HOW that hole is connected to the injector pathway. I've attached a picture. Curious as to advice from folks, is that shiny piece of metal supposed to be there? And is there supposed to be a bearing in the injector shaft as some of the videos seem to imply w/ similar looking carbs?

Maybe I figured it out. I found a WM36 and WM23 on ebay FINALLY, that had to boring directional pictures of the carb I needed. I see the bearing looking object in both of those. Thus its probably just the way it is built. Now I just have to figure out whether the WMC39 had a check ball. It seems to fit in nicely so I'm going to try it and see what results I get I guess.