The hole into which the tab/spring goes has some tiny plastic parts in it that work with the spring and tab. We can see in the 2nd pic that the flanges at the bottom the tab slides easily into the slot, and the tab itself into that hole... Sorry about all the cat hair! I've been careless about keeping this clean as I've been working on it.
In the 2nd pic I haven't pressed the tab into its slot yet, so that you can see how it would fit in there. But you'll need to actually put it in there if it pops out!
Last edited by beermeister kink; 01-29-2013 at 10:18 AM.