Replacing lower spray arm KitchenAid dishwasher

Hello,
I took off my lower spray arm to clean it out and now I cannot get it back so that it fits snugly and doesn’t wobble. The only parts are the hand-tightened nut that goes on top, a washer for that nut, and a split plastic seal ring.

It seems really simple, but I must be overlooking something…
Thanks

Video’s to help
http://www.youtube.com/results?search_query=kitchen%20ain%20bottom%20spray%20arm&oq=kitchen%20ain%20bottom%20spray%20arm&gs_l=youtube.3...72.3982.0.4447.25.20.0.0.0.2.489.4063.2j4j3j5j2.16.0...0.0...1ac.1.11.youtube.qbAq0BGcE84

I watched several videos but they were no help. IN each instance the rotating blade assembly seemed to pop right back on with no tools required. A couple mentioned some "jiggling" but I have no idea what/where I am supposed to jiggle. The rotor isn’t remotely close to being firmly seated.

I’d hate to call in a pro for what will probably be a five minute job. I still think i am missing something fundamental. Could I have mislaid a part? The users’ and installation manuals don;t show schematics of this assembly.

Sorry can’t be much help maybe next time pay more attention before dismantling something and take pics with your phone or write part numbers down on paper and tag stuff.

True that. It just seemed so darned simple.

It actually is it took me awhile to get it when i first started appliances the formula is there in front of your face and it’s rather simple…concentrate danielson!