So i have a Riello 40 F5 a little newer than in the picture below. I have the same problem but when i unscrew the nipple-like-screw nothing comes out. I need help!!!!!
Here are a few pix.
Let me know which one i need to bleed or unscrew

http://img534.imageshack.us/img534/1421/img2109j.jpg
http://img693.imageshack.us/img693/2689/img2108a.jpg

Van, March 2010