i purchased a use NH 450 sickle. i have a kubota L245. i was cutting a field and the bottom connecting shaft busted. temp fixed it and it did the same thing to the other side of that shaft. the pto is in 1st so is running at 540 rpm's, the tractor is running in 1st (the tach is broke) at about 2/3 power. any explanation would be greatly appreciated.