Top shelf not cleaning

Hello everyone, I am new here. And I have a dishwasher that stopped cleaning the top shelf a few months back.

I have cleaned every filter, ran water through every tube, visually inspected each tube when possible, and its still not working. As a troubleshooting step, I put the dishwasher on 1 hours wash to get it to run the motor/pump the longest, and then I quickly open the door while looking at the top spray arm. Nothing is coming out.

I’m convinced its not a filter issue, nor a blockage issue. What’s my next step to try to fix?

When I cleaned it out today there was some crud inside of course, but nothing that would cause any major blockage.

In the past I have replaced the chopper assembly as I took it apart once and it never seemed to go back together exactly right again. The metal "snap nut" on the end of the plastic finger didn’t sit right. The plastic was kinda messed up.

Another question kinda related here. How does the blue plastic manifold work? I see there are two balls in the bottom elbow. I’m thinking that the motor/pump runs at two different speeds. High speed will force the balls up sealing off a way for the water to get up to this manifold. Leaving the only path that of the upper shelf. Running a lower speed will not be enough for the heavy balls to seal off, and then the water will flow up through the blue manifold. In my mind the motor may not be getting into this faster speed, causing all of the water to flow out of the lower blue manifold. Does this make any sense. Any chance this is my problem?