If any of the other sources don't work, you can try either
Lanier Engineering or
Motion Industries. I have used them both in previous years to get pneumatics spares, including the SMC double solenoid valves (specifically, I got these through the Lanier outlet in Newport News, VA). They usually have the parts in stock, and will ship over night. Good luck!
-dave
-------------------
I used to go away for weeks in a state of confusion.
-- Albert Einstein