I broke the PTO shaft outside the tractor hub and it continued to run just fine until I replaced the PTO Shaft in my TO20 about 2 months ago, which seemed pretty simple. I know at the time, after the installment I was able to place the PTO in gear with ease when the was tractor running, but since that time I had no reason to move the tractor. I can't believe I didn't check to make sure that I could put the tractor in forward or reverse, again I'm certain that I did. Well, today after agreeing to sale the tractor, I could not get the tractor to go into gear while running. Occasionally, it would slip into reverse. When the tractor is off, I can place the PTO in gear as well as put the tractor in forward or reverse. Also, now when the PTO is running and I push in the clutch, the PTO does not stop running. What could have I done wrong? Should the tractor have been in or out of gear when changing the PTO or does in matter?