Home Depot sells water pressure gauge ~$12. The pressure nut is double nutted meaning you have to loosen the lock nut first, then loosen the pressure bolt. Flow some water and recheck gauge. Easy.
You might keep an eye on the gauge when someone in the house turns on faucet. Should be same pressure. If it drops=bad regulator.
If you guys are so inclined, and want to spend about $400, you can install another pressure regular just after the meter. This will reduce the pressure to the landscaping. Advantage is less atomization at the spray heads. Bigger raindrops=more gets on the ground.
Another way is the install a smaller pressure reducer at the beginning of each sprinkler manifold.
