Our dishwasher was leaving greasy residue on dishes and not cleaning well at all.

Four screws hold the entire water dispersion apparatus to the bottom of the dishwasher. I removed the four screws, and got access to the single screw holding the diffuser to the motor shaft. After prompt delivery of the four items needing to be replaced, the installation was a breeze. I placed the new spray arm on the diffuser assembly with a new nut, and then placed the entire assembly over the screw holes on the bottom of the dishwasher, then replacing the four screws. Mission accomplished, and clean dishes once again!
Thanks for the diagrams for parts identification and replacement, PartSelect!