MANIFOLD W10671899

Water comes out of lower spray arm, but none out of the manifold or upper spray arm. Upper spray arm hole are not clogged. There is some slop in the upper bearing (if there is one) in the circulation pump, but it does generate enough pressure to slowly rotate the arm and spray barely reaches the top of the Dishwasher. Advice?

I asked a question recently about not getting flow out of either the spray manifold or the upper and middle spray arms. You suggested I look for a clogged passageway. Neither the manifold nor the tubes that serve both the middle spray arm and the top sprayer are clogged. I noticed after removing that assembly that there is a disc with a round hole in it above the pump, below the spray arm tube connections. It looks like it may rotate to alternately supply water to the various manifolds. Is this True? Perhaps it is not rotating? How can I fix it? All tubes and orifices are clear. Pump has slop on upper bearing (if there even is one) maybe pump works but pressure is low for some reason? It squirts water out of the lower spray arm that barely reaches the top of the dishwasher. Is that the right amount of pressure? Hate to replace the pump if it's not the problem. Please help. Thank you!