OK, it's fixed.
It was indeed the spray nozzle.
The gun shoots water just fine now, even though there is a slight flutter.
The flutter is most likely caused because I didn't tighten the nozzle
enough, (from the DeVilbiss manual), I was just to much in a hurry to test
the gun.
Will adjust and try paint next weekend.

Thanks again, to all that gave me help with this problem. Ten years ago my
eye sight was better and I would have caught that crack in the nozzle.

Ray