a failed master cylinder sounds like a possibility, but i'm not sure if this is the most likely one. originally a clutch line failed (rusted out). the failed section was easy to find because the fluid was sprayed on the frame and all over the ground. prior to the line failure the clutch was working perfectly. after I replaced the leaky section of clutch line I was unable to bleed the line; a few bubbles and some fluid came out the hose but the clutch pedal would not return to the "up"/normal" position. I am just a little surprised that the line and the master cylinder would fail right after one another.