I have 40 of these heads around the property. We just moved into the home and I was trying to adjust the spray distance with the screw on top to no avail. I took one apart and noticed that the (for lack of a better term)sleeve that fits into the bottom of the head that is used as a stop for the screw head and subsequently cuts off the water flow is missing. I suspect they are missing on all of the heads. Is ther a way to purchase this part?