I am having a problem with my sickle. It was working fine up till last week. Then suddenly it would vibrate and shudder after a few feet and pop off its center mounts on the tractor. I remounted it several times unable to figure out what the issue was. Well I got it on the last time and put the incredible Hulk torque on the mounting bolts. It stayed on this time but then it threw the belt. When I looked back I saw that the pulley on the sickle itself was sticking out the back about 8" I could see the drive shaft. I am able to push it back in but have not run it. The driveshaft should be connected from the pulley to the flywheel I believe. So my question, Is there a pin or key that holds the drive shaft into the flywheel on the front. If this pin or key broke would it cause the vibration and shuddering. Someone with more knowledge please post thoughts or instruction.
1964 CUB CADET 100
23A Disc,2-C-22 sickles,54 Blade,152 disc,38a lift disc,C2 Mower,Kub Klipper, and a side dresser.