why is my sprinker leaking water all the time: Hunter PGV valve repairs

Problem: water leaks out from the sprinkler head continuously.
Solution: open up the valve housing and flush out, clean the diaphragm and reinstall.  
Follow up:  If cleaning out the valve housing did not solve the problem, use new diaphragm and reinstall.

For year 2021, CO requires water tight sprinkler head to prevent leakage.