If you look at the first picture, you can see the end of the floor lever linkage where it pushes against the "button" of the valve. The tee at the other end distributes the oil to each of the two cylinders. Without me messing around with it a bit more I believe the lever either pushes the button or doesn't. There is no way to "feel" where the lever is during operation as that button moves maybe only an inch or so. I agree that there should be some way to control how high you want the bed to go and maybe that is the clutch.
