End pin keeps extending when I pick Double Bass up.

So I just got my double bass and I am renting it. Whenever I pick the Bass up it extends till i put it down it is the lowest. I don't know if this is normal or not. I need a fix or something to help.

Edit: I fixed it! The screw wasn't in the place it was supposed to be in. And there was a hole inside the hole where the screw is and that is were the screw should be. But mine wasn't. So I took the screw out and put it in the hole.