According to my manual on the auxiliary hydraulics the #1 valve controls the three point lift. You can set the levers on the side of the seat to constant pumping and use the aux. valve or lock the aux. valve in the up position and use the hydra levers beside the seat. I bought a mf65 with the aux. valves but it has a bad pump in it. I want to take the valves off of it and put on my mf50. I just haven't done it yet. I do need to get it done and then I can get a better understanding of it.