Sprinkler station pulsating - won't shut off
I have three stations in my backyard. Two work fine, but the third (Rainbird - sorry don't have a model #) has begun pulsating water through the sprinkler heads rather than spray. The only way that I can turn it off is to turn off the main vein of my landscaping irrigation. Attempting to do it at the station or using the timer control panel is useless. I opened it up hoping to find a diaphragm that I could replace, but the only thing inside the cap is a washer. Could this be a solenoid issue? This station is less than a year old and worked fine all last season.
Thanks in advance!