How the Laser bailer o-rings are attached. 

Bailer o-rings This is my best attempt to show how the Laser o-rings attach the bailer shute to the bailer itself. I have circled red where the o-rings attach to the hooks on the bailer down to the shuttle which cause a constant pressure trying to keep the shute closed.

They designed it so that when the rod is pulled, it pushes a lever down which props the shute open. When you push the rod in it allows the rubber o-rings to pull the shute to the closed position.
Bailer Shute
This is the picture of the bailer shute itself. I have circled in red the actual hook built onto the shute where you place the other end of the o-ring. The engineer has an o-ring for each side of the bailer so that it pulls the shute with even pressure.