Question
 I have a rain dial plus irrigation system.  I noticed in one of my zones, my front yard and most important zone, that the sprinkler heads are spraying with less than normal velocity.  All of the other zones are spraying at the normal velocity.  I checked the valve and it seems to be turning on and off properly.  I have either the 2500 or the 205 Irritrol Valve system.  The problem seems to me that I have a clogged screen, but I can not find any information if the system has screens and if so where are they located.

Answer
Thanks for your question.
Most sprinklers have screens inside of them. For the spray sprinklers they are located just under the nozzle. The nozzles screw-off counterclockwise. Once reinstalled you will need to readjust the spray to the correct direction. This is done by turning the entire sprinkler.
With the rotor sprinklers the screen is in the bottom of the sprinkler. For these you need to dig around the top of the head and unscrew the cap. The working parts and screen will then lift out. You will need to readjust these also after reinstalling them
Hope this helps.

Matt