If you don't see any fluid up top, my bet is that it is leaking at the slave inside the bell housing. Easy rebuild or just replace the slave. While your at it, rebuild the master as well. That is a little tougher as you need to be a contortionist to get at the bolts inside the car and on the other side of the firewall. I have also seen the steel tube wear a hole in it where it passes along the dust shield on the bell housing. FYI, TSI imports sells a braided stainless hose that goes from the master all the way to the slave. I like it better than the metal pipe. If you rebuild both, go with dot 5 silicon fluid after your done. It works great in the clutch hydraulics, just don't use it in the brake system.