The Pto shift lever broke on my Massey Ferguson 231. I took the old shifter out and when trying to put the new one in the large Pto gear wont slide back far enough to get the shifter into the groove on the front of the gear. I don't see anything that should hold that gear from sliding freely back and forth on the pto shaft. Am I missing something or is this gear just being a pain in the old backside? I have even tapped it with a crowbar to see if it may have been frozen up or something and it wont budge. Any help will be appreciated.