I found a valve today, picture 1, that (I believe) has a line coming from the 120v compressor, a line going to the rear manifolds and a line going to the small supply tank. It has 2 shut off valves. I sent pics to Newell and am going to have to wait until Monday to see what they think. I'm not in any rush and I don't want to break anything in the process of fixing the problem. If you're talking about the same thing in picture 1, I checked this today and there is plenty of air going thru, however no air goes from this to the manifolds. Actually, the blue line you can see in the picture that runs thru the frame rail is the line that feeds the manifold, and comes from the valve in picture 1 which is located between the drive axle and the transmission cooling fans
I have never been to the Woodward Dream Cruise but it is definitely on my bucket list. Have a great weekend, I'm sure we will meet one of these days