Had this problem too. Check and repair or replace the following items:
1. Remove Clutch pedal. The hole where the clevis pin connects to the
master cylinder pushrod wears into an egg shaped hole.
2. While you're there, the master cylinder pushrod also wears into an egg
3. Replace the clevis pin too. it wears down to a small egg shaped pin.
Together the three items above can be the difference between the clutch fully
disengaging or not. Simple solution is to drill the hole up to the next size
available bolt. use one that the threads stop 3/4 of an inch from the head,
then cut off the threads. Drill a small hole in the bolt to accept a cotter
4. Replace rubber flex hose between slave and frame. It ballons up when you
press on the clutch pedal.
5. The slave push rod and clevis pin also need checked, same as at the
the clutch system self adjusts. Don't bother making the slave pushrod any
longer, it doesn't help.
Dave Riker, 69 Midget