Wow! Thanks for the quick response. The reduced pressure and performace are "new".
I have cleaned and checked all heads and nozzles. The "chattering" of the valve occurs when at least one of the two "problem" zones
is running. And only when the 6-port unit is operational. The port has been replaced. There just seems to be a connection between the
noisey valve and the reduced performance. Other than the reduced pressure, the only other evidence of reduced performance is the
debris and "dirt" left in the "problem" zones. The 6-port unit is still under warranty and I have considered exchanging it. There is no
evidence of malfunction on the unit. The gushing and "chattering" noises seem new. The pressure on the 3+1 unit are very high as they
should be.
The noise from the Ortega valve is (now) constant when the "problem" zones are operating. I don't recall such audible activity previously.
Very frustrating.