when I took mine apart the same pressure switch was there, with two places to push the tube. I cut a little bit , 4mm, off the end to give a tight fit then replaced it. It was attached to teh larger diameter side of the sensor ie the part furthest from the PCBoard. I presume the other side is for switching for something which switching when the pressure falls below a level at which it needs maintaining. Anyhow it is definetly the side furthest away from the board that mine is attached to.
Rob, November 2013
