When I had my spec 3+ clutch installed and the zzp adjustable rod, they had difficulty bleeding and it was never bled properly (had to pump it up a little bit every morning) So I bought a vaccuum bleeder to do it myself. I hook it up to the bleeder screw on the distribution block put some vacuum to it and nothing was coming out so I went old school. I got some help had him depress and hold the clutch down, open the bleeder screw fluid comes out, close the screw the pedal stays on the floor, does not return. After exhausting all the other possible ways of bleeding I call it quits for the day grab a beer and remember I have a new clutch master cylinder sitting in a box. I take it out to see if something would come to mind.... and something that I have never read or heard comes to mind if the plunger portion is NOT fully retracted even depressed about 1/16" no fluid can enter the cylinder from the resevoir. So I loosen the adjustable rod ensure the plunger is all the way out. Vacuum bleed from the bleeder screw and guess what? Out comes fluid!!!! 4 bleedings with pedal pumping in between and I'm done in 20 minutes!