A few things in the manufacturing of strikes can lead to this loose condition,
1- the outside ring was a few thousandths blanked/cut too large.
2 -the inner silver planchette was too small.
3 -the process of mating these pieces didn’t have sufficient die pressure to mechanically bond/ squeeze the metals into a solid contact together.
4 - they’re pressed in one way and only one way, if you were to take one apart you would see the metal galling lines/ scraps. This indicates the press force direction and if you were to apply a force/ hit On the center silver section in the opposite direction it will come out sometimes with little or minor resistance.
5 - when they have fallen out they can be realigned by matching the proper Metal rifling/ scratch marks and fitting level the pieces back together, this must be done with soft cotton material protection on both sides and using a jack press. Not an easy task. Hand inserted also works, but is not as strong of a bond.
Just a little FYI
Gabe Dobos
On the Detroit River