I have a 53 Super C and recently bought a Sickle bar mower for it. I had engaged the pto before but never used it for anything before this so I thought mine worked too. Well after monkeying around with the mower set up for a day I was ready to go mowing but when I engaged the pto it didn't do anything but the belt pulley was going. So I took the pto assembly and shaft out and found that the woodruff key in the actuating mechanism casing was sheared off. It looked as though it wasn't quite the right size one that was in there, seems this probably had happened to the previous owner and he put in whatever he had around. It's really simple and self explainatory to do when you get it apart the worst part was getting the inner end of the pto shaft back in place beacause the shaft goes in about 2 and a half feet to where it meshes with its gears but I just messed with it for a minutes and she finally slid into place.