8 3/4 rear end confusion

I finally decided to go the easy route and shine a light through the axle housing to see what's in there, I know I should have done this from the beginning. And of course, I see the button laying out of place. I took it out with a magnet and attached pics of how it was sitting in the housing, how the button looks, and the pin next to the button still on the magnet. Do I just need to get this button with the pin going through it back into that hole? Is there a second button somewhere that I can't see? When looking inside, it seems like there is only one hole for one button. Thank you everyone, I really appreciate it!

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