Massey Ferguson 65 clutch won''t release after I fixed it

Yesterday I bought a Massey Ferguson 65. Today I broke it. The tractor was working fine except that you could not disengage the pto with the clutch. The ground clutch was working fine. You could easily put it in gear and engagement would start as you release the pedal about half way. An issue that concerned me was that the clutch safety starter switch has been bypassed. I removed the switch and found it to be working fine. My conclusion was that there was too much free play in the clutch linkage and this explains both problems. There was no adjustment left in the pedal linkage, it had been run out to the very last threads. I decided to remove the pedal, linkage turnbuckle and the lever from the clutch actuator shaft in ordered to restore the worn out egg shaped holes. After repairing the linkage and putting it back on the tractor I had regained all of the threads in the turnbuckles. I was very satisfied with my repair until I discovered that I can't disengage the clutch at all now. Something has happened inside the case and the clutch will not release. It's not anything to do with linkage adjustment. The pedal is very stiff and if I start the tractor in gear the clutch will slip but you have to hold the brake not to roll away. I have observed through the hole in the bell housing that the throw out bearing is against the fingers and that the pressure plate will move as soon as you start to depress the pedal. There is no free play anywhere. My guess is something is wrong with the linkage at the throw out bearing. Sorry for the long story but I am really hoping that some Massey Ferguson whizz can tell me how how I screwed this up and what do I do next.