If you have put new dog agits in,be sure that small rounded end of the agit slides up in to the small round slot of the white agit holder piece. You will have to slide the black ring downward in order to remove the old broke agit pieces ( I had to do this for my installation) The agits will be secured in the white holder when you are done.
http://repair2000.com/agitate.htm
Vinny the repairman, May 2007