How's That Made?

I was wondering specifically, how do they get the "retention ball" into a ratchet wrench drive, or on extension bars. At about 3:20 into this video:

The show a quick explanation. Still, I would think a spring must go into the cavity too, so that the ball stays at the front. Also, Jet ratchets (for one) have a button on the back of the head that you must press to push on (or pull off) a socket.

Anyway, it's always immensely interesting to me, seeing the steps in making things.