After further research, and a timely call from Roger Engdahl, he determined the 'check valve' was probably the culprit all along. When removed, the check valve just fell apart. Install new brass $20 piece and all is well. Access to the check valve was easy. In the outside bay area behind the hose reel. The solenoids were probably never in the equation. I say plural because this coach originally tapped for an 'instant hot water' dispenser that was never installed to our knowledge. The second solenoid had red pex installed on it instead of blue.
Thanks to everyone's help. Ronnie at Foretravel has been updated as well. David