The old sprayer hub had worn to where one side was worn through and the other edge was still almost as thick as the new one. I think the sprayarm bearing had worn through at some point and was no longer providing protection between the moving parts. I replaced both parts and the dishes seem to be much cleaner. Another forum mentioned that water pressure could be lost through 'gaps' like that and cleaning would be effected. I also had to clean soap scum out of some of the ports on the middle spray arm. This allowed the arm to spin better during cleaning. Another item I replaced was the spray tube that goes up the back of the tube and has the flapper valves for the center rack in it. Those had become calcified and would not close anymore allowing water pressure for the center spray arm to be lost. Replacing the flapper valves seemed to help with cleaning as well. Dishes come out nice and clean now. I also fixed a minor leak near the front right-side of the door. I had to tighten the large plastic nut that holds the float assembly in. It was about 3/4 to 1 turn loose and caused the leak. Tightening the nut cured the leak.