Sprinkler heads only coming up halfway
The sprinklers on my lawn is only coming up halfway. They were all working before. I turned the zone on the other day at the valve manually and I'm not getting enough pressure to fully raise the sprinkler heads. Sometimes I can get the sprinklers to stay up by pulling them up manually, but only after running the zone for maybe 5 minutes, otherwise they drop back halfway down. I'm thinking there must be a break in the zone causing a pressure drop.
Trying to find the break will be a challenge. An earlier post mentioned caping the sprinkler heads and looking for wet spots after a while. But since my issue is in a lawn, I think that might be difficult to spot thru the grass.
Can the valve contribute to this? The valve is wide open is full ccw position.
Any help would be appreciated. Thanks.