Entering this in the archives for the record:

I had a badly stuck purge valve that I fixed tonight. If spraying WD-40 into the vacuum hose doesn't work, try spraying directly into the valve (both sides) and then turn the valve upside down and let it sit. After a few minutes, turn it back over, shake any extra WD 40 out, and apply about 16V to the terminals repeatedly until it starts clicking. The voltage is a little higher than spec, but it will help force the solenoid to actuate. Repeat if necessary.

To test it when you're done, try to blow through the valve. You shouldn't be able to blow unless you apply current to the terminals, which will open the valve.