Make sure there arent any leaks at the rubber "flex" hose between the hard lines under the clutch master over to the bell housing. Sometimes this hose will also be weak from age and collapse partially as pressure is let off the clutch pedal. Don't bother looking for a replacement, there is none. You need to find a piece of ready made brake hose that has the 1/4" npt female fitting on each end to use as a substitute. Also check to make sure that the hard line going over the bell housing didn't get kinked when you were replacing the slave. HTH.