You may have an old door knob like mine, and
if you get trapped in a room, that’s not a good thing. The problem with this is that
the set screw is come loose. And that’s simply this little, flat adjusting screw here
that you’ll tighten.
First let me show you what is involved here and what it’s
holding on to to help you better understand. On the old hardware of this ilk, this is a
simply a threaded square rod that this screws onto. So what you’ll want to do is screw
it on as far as it will go, and then once it’s tight, you want to back off a little
bit because you need to leave some play in there for it to be able to turn easily.
So once you’ve got it in the right position, then you’ll simply tighten the set screw
until it presses up against that square threaded rod on the side. And then you’re free.