Hi, I recently had a new irrigation system installed, it is a 2 inch point with a 2 inch brass check valve mounted vertically at the top of point, the pump is located about 20 ft from the point so there is a 2 inch line run to the pump. I have had the guys who installed it back twice and they have been nothing but professional (they do seem to be a little confused on what is going on though), they have changed the check valve, pressure tested and leak tested all the piping and fittings and have tried different depths for the well point ( .I have also inspected every sprinkler head and replace any that were leaking or where questionable and also cleaned the screens in all of them) When the system is turned on, you get great pressure and water, then after a little while the heads will either drop down partially or all the way back in the ground and in a few seconds pop back up. Any ideas? my only thought is that there is not enough water in the well to keep up. thanks for any suggestions.