[cwl1979]

If you take the arm of the height rod, when you lift it up it should empty the bags, when you push it down it should fill them, looking at your picture the rod is angled upwards and not lowering the bags. I would rotate 180 on the square valve body. Air inlet is usually a side port and air outlet to the bags is usually a side port. the bottom should be an exhaust port. the 4th port should be plugged.