Irritrol's fixed-radius pop-up lawn sprinkers allow easy adjustment using nothing more than a flat-blade screwdriver and your bare hands. Sprinkler head types control arc and radius of the spray, but parts are easily interchanged for more radical adjustment. A gradual reduction in coverage probably indicates the nozzle needs cleaning, not adjusting. With only slight changes to the product line over many years, all Irritrol sprinklers should be adjustable with the same general procedures.
Turn on the sprinkler system briefly and mark the position of any sprinkler heads otherwise hidden from view. Note which sprinklers give good coverage and where coverage falls short.
Select a sprinkler head that is not performing correctly and turn the system off. Pull the sprinkler head up manually. Newer models include a finger tab, but older types may be difficult to grip.
Check the pattern embossed in the sprinkler head cap. The pattern indicates the arc the cap covers and the direction of the spray. Correct the direction by rotating the shaft of the sprinkler head, not the base. Five pounds of pressure should cause the retaining gear to skip. Aim the head in the desired direction.
Change the coverage arc with interchangeable spray heads preset to arcs of 90 degrees to 360 degrees. Unscrew the cap at the end of the riser tube and replace with a cap providing the preferred pattern.
Adjust flow rate by tightening or loosening the screw in the center of the sprinkler head when the system runs. Turning counterclockwise increases flow, and turning clockwise decreases flow. Opening this valve should restore full flow if the system works at full pressure.
If turning the screw counterclockwise does not increase the flow, turn off the system and unscrew the sprinkler head cap at the top of the riser tube (the tube that lifts from the yard when the system runs). Clean or replace the plastic cone screen. Reassemble and adjust the sprinkler.
Change the area of coverage with the new I-Pro series heads by selecting color-coded nozzles with different angles of spray. The higher the trajectory of spray, the more area the sprinkler irrigates.