I'm glad I found this old post. Cause now I have my tiller attachment off and can spin the tines sometimes real easy and then it locks up. Betting its either key 7 or 11 this time.
I am having the same problem right now (have a post in this forum detailing it)
Can you explain exactly how you solved this issue? I still have the bolt on the end of the arm, but the whole shaft is sliding along the big nut/plug (part 27)