Check out quattroworld, lots of PCV posts there. Its really very simply made, just a orange rubber diaphragm in a two-piece plastic casing, and a return spring. Its easy to dismantle.
I can only think of two reasons why it wouldnt work:
1. its so clogged up with caked oil the diaphragm cant move properly
2. the diaphragm is punctured or disintegrated
http://forums.quattroworld.com/a8/msgs/80088.phtml
http://forums.quattroworld.com/a8/msgs/79849.phtml
Here is a post with a picture:
http://forums.quattroworld.com/a8/msgs/70936.phtml