I have a 16 zone irrigation system put in by the previous owners of our house that I am having trouble with. It is a Rainbird system. I am having a few problems and do not know what could be the causes. I've had a couple professionals in to look but am hearing different stories so do not know what to do.

#1 -- donut rings. In some zones I get a two foot green circle around the sprinkler heads then poor coverage around that. An hour and I have less than 1/4". It is not a water pressure issue from my well as other zones with the same number of heads are fine. They look like they are working but clearly not doing the job. I have adjusted the spray so it distributes the water well and that helped a bit but of course now I am short on distance. The area around some of the sprinkler heads is VERY wet (you can step and squish water). Is this normal or could this be the problem. How wet should it be right near the sprinkler head? Could that more likely be a leak in the sprinkler head or pipe attachment or either?

#2 -- similar problem in a couple of zones I have very poor pressure (sometimes not even enough to turn the heads). It is worse this year. I've run that zone for a couple hours and cannot find any soft spots in the lawn where I think the pipes might be (the installer did a poor job and there appears to be no logic in how they go!). Again I have a lot of water around where the sprinkler heads are and green circles. It may again be same as #1 but I have read about leaks in the valves? What does this mean and are the valves where my boxes are or at each sprinkler head? How would I know if this is the problem?

Sorry for the long question but before I pay someone I'd like to have a general idea they can fix the problem. I don't mind paying to put in new sprinkler heads (apparantley these were poor quality ones put in cheap) but want to make sure I spend my money wisely.

Thanks

Sharon