Clutch problems

Help! I wrote earlier about not being able to get my car into gear while the engine is running. I bled the clutch system a number of times now. The pedal eventually gets stiff, and then within minutes gets loose again. I replaced the slave cylinder. I rebuilt the clutch master cylinder. I don't know if it makes a difference, but the slave cover gets pushed off when I depress the pedal a few times. I am figuring it still has to be the slave cylinder or master cylinder that is not working. Can anyone tell me how to tell which one is the culpret? Is there something else I am overlooking? This is the last problem to deal with for me to make my first test run after working on this car for the past year.
Thanks, Kevin

Are you loosing fluid out of the system? Do you have a balloon effect on the line from the master to the slave? If not, have some one look at the master reservoir when you push in the clutch. The fluid level should drop. If the master is leaking, the fluid level will come back up even though you keep the clutch pedal on the floor. If the level does not increase, then I would suspect the slave. After the big work you did on the pin, disk, bearing etc., I am glad to hear the problem is on the "out side".

Thanks for the help. There is no fluid leaking. I did not notice a ballooning effect, but I wasn't watching very carefully last night. Considering the hose is 25 years old, it is certainly a possibility. I'll try your suggestion about observing the master cylinder also when I have help tonight. My first guess (hope) is that it is the master cylinder.Thanks again for your help.
Kevin