1994 Porsche Clutch Pedal

I have a 1994 C4, (964) Factory TurboLook with a clutch pedal problem. Both when fully warm, and when cold, after being parked for a few days, the clutch pedal remains almost completely depressed and the clutch disengaged. After pulling the pedal out manually – which is met with only moderate resistance – the problem goes away and everything, engine, clutch, shifting, transmission, appear to function properly.
My independent mechanic believed a fluid line (utilizing the master brake fluid supply) was likely swollen, resulting in this condition. We replaced this line (which, after being exposed through a good deal of labor, did NOT appear swollen or damaged) as a precaution. The symptom reappeared after being run very briefly to wash the car and then returned to the garage. I am almost certain that, on this occurrence, the clutch pedal was in the “engaged” position and the car left in first gear. My mechanic thought it was fully possible that a leak in the one of the two (front or rear) cylinder resulted in the pedal being “pulled” back to the fully depressed position as fluids cooled while the car sat un-run for a few days.
What do you think? Where would you look?
Thanks very much. Pacman