[Marshall V. Daut]

Check for a crack in the clutch arm where you adjusted the free play. These arms often don't crack and break dramatically. Usually they start to crack, which changes the clutch adjustment. People think the clutch disk has worn a little, so they re-adjust the clutch pedal travel without looking at the clutch arm. Then the crack travels farther and the clutch is out of adjustment again. By this time, the arm may split in two.
Examine the clutch arm at its base where the shaft goes through it. I'll bet it's cracked, given the sudden change in shifting ease and pedal travel.
Marshall