Outside sprinkler leak

[swiffycat]

There is a drip that keeps happening from our outside sprinkler. Anyone know the cause of the problem or what to do about it? I circled the area where the drop occurs from.

 

[Geofd]

Is it constant or sporadic, if it's constant you may have to rebuild the backflow preventer,if it's sporadic, you may just need a check valve in front of the backflow preventer.if this is the first time running it you can try bleeding the test ports (were the flat head screw driver test ports are)