If it still doesn't turn off automatically
If you want to take your ASOV apart to see if something has gotten into it that stops it from functioning correctly, disconnect the tubing as described above, and remove the four screws. Carefully open it up and take care to make sure you remember the order of the inner parts you remove, so you can put them back together in the same order. Inside is an O-ring, a small membrane, a drum, another membrane and O-ring. You could inspect it for any obvious issues. Taking it apart will take all of a couple of minutes, and it might start working again once you're done. It must be reinstalled in the exact same orientation. I recommend taking a picture with your camera or smart phone to match up everything during re-installation.