Sprinkler Head Trimmer Rainbird Sprinkler Head Sprays Fine To The Right, Dribbles To Left.?

Rainbird sprinkler head sprays fine to the right, dribbles to left.? - sprinkler head trimmer

My house water (irrigation), the system uses a computer Rainbard. One head is to spray some kind of fly patterns to the left and right (number of nozzles 15SST) sprays a fine side, the other only leads - as if the disability. I cleaned, and it made no difference. I replaced the nozzle and the filter below, and it did not make any difference. What in the world, the cause might be?