The agitator lift off, but it is sometimes hard to do. Here is a photo of how one site does it. Be careful, it can come loose and smack you in the face. (Been there)

According To Ge Web Site It Requires A Repairman But If You Are Carefull It Lifts Off With Some Force By Getting Your Hands Under Each Side And Pulling Up. Just Remember To Keep Your Face Away From The Area Because It Does Pop Off When It Lets Go. There Are Fingers Inside That Latch Down Over The Edge Of Each Of The Catches Of The Agitator Coupling. I Have Been Told That If You Add Vaseline To To The Areas Were The Fingers Latch To It Will Come Off Easier The Next Time.