The top part of the agitator comes apart and there is another housing part inside which has the cams in it. This part snaps onto 2 plastic tabs. Seems to snap in good but it doesn't stay.
Upper 1/2 should be bolted down to the lower 1/2 with a bolt ( #5 )...this bolt runs in the agitator shaft...make sure none of the threads on the bolt or inside the shaft are stripped.
Nothing else should hold the upper 1/2 to the lower 1/2.