Short of any faults inside the clutch, the problem is likely to be nothing more than adjustment. As has been said, remove the cover under the clutch housing. Give it a good wipe it will probably be quite greasey. Turn the flywheel by hand and you will see 3 equally spaced adjusting bolts with locknuts around the outside. This is the adjustment that determines the dis-engagement point in the travel of the clutch pedal. You will need 2 good 1/2" AF spanners and a bit of patience. Without going into sizes the approximate thickness of gauge you need is two hand hacksaw blades back to back with the teeth ground off or something similar. The thickness is less important that having them adjusted the same. Slacken the lock nut until you can just turn (unscrew) the bolt. Adjust and lock for the three.
At the front of the clutch rod is the short operating arm. Ensure that the clevis is located in the forward hole. Free travel on the pedal should give a clearance of approx 3/8" at the point where it makes contact with the casing. If not, adjust with the lock bolt at the bottom.
If everything is OK you should now have a PTO that will stop with at least 1 to 1 1/2 " of travel still on the pedal. Check also the amount of play in the pedal pivot bushing. You can loose a lot of movement here. For the sake of comfort you may need to lengthen the rod slightly to lower the pedal but make sure you have the pedal travel as above.