Yeah, did that.
I am pretty sure that I actually had the solenoid screwed down too tight against the manifold. For some reason, if I ease the manifold back a bit, the flow returns.
*UPDATE* - That wasn't it. Worked for about 30 minutes then flow came to a complete halt again. I am now considering that it is my diffuser - it is brand new (well used for a few days), but just wondering if it could be causing enough back pressure to warrant what looks like a stop in flow.