Why does the PTO axis do not rotate, even after connecting the clutch and the Light of the PTO is on?
You will notice that the transmission shaft goes from the clutch on the motor to the gearbox at the back of your tractor. This reduces the RPM at the speed of the PTO and hosts a gear lever that connects and disconnects the PTO. Examine the clutch hand lever. That lever can be folded and could prevent the clutch from coupling. Then check the linkage of the rear gearbox. Make sure that it is not disconnected or bending either. You will see an axis that crosses the box located in the upper left, and looking from behind, the shaft moves the gear lever inside. You may have to try to disconnect the outer rod and use jaws to exercise the lever.
Finally, try turning the transmission tree manually. When it moves in a sense, it should be free, rotating very easily. When traveling to the other side, it should be connected to the PTO transmission shaft, to the clutch, and rotate with much more difficulty. When you see the indicator light of the illuminated PTO, understand that light represents the coupling. The coupling inside the rear gearbox is not really detecting. Also, if the clutch of the PTO and the gearbox are coupled, and the PTO is still unloaded, then your problem is probably extensive. It is inside, and the process to fix it will be extremely complicated.