PTO Shaft joint replacement

[IH3444]

Hello, has anyone ever replaced the PTO shaft joint. I want to change mine out to one for a piece of equipent I want to run off the tractor PTO. I am having trouble getting the plastic guard removed. I see the lock/unlock latch on the guard, and have tried multiple times with a screw driver, turning this plastic lock, but the guard will not remove. I have tried both directs, turning all positions, twisted the plastic guard around, but it will just not pull off. I was hoping that someone has replaced their joint before, and has experience with this. I was going to reinstall the guard back on, for safety, and protection. Thanks for any help, and directing me to any website which may explain this.