check the heads to be sure that they were installed at grade level and not below grade. Also, if they are not straight with the ground surface and also if the radius adjustment screw is turned down too much it will create more water spray directly in front of the head. You should not have to change the heads.

I had the installer come back and check them. He said they were fine, that the problem was the soil around them is too fine. He suggested I put sod around the heads, to about four feet away from them. I didn't ask him about changing the heads to something different, though.