Rem. the top of the agitator (pry it up gently)
down inside there you'll see three "dogs" which give the upper agitator it's back & forth action, and are worn out. At the center you'll see a bolt head (or screw head, not sure which)
Unscrew this to rem the top piece, replace the dogs and you're good to go
Jim in Quincy MA, August 2006