Check the upper spray arm for cracks or splits. Make sure that the upper rack is pushed all of the way in before starting a cycle so that the manifold will dock properly to provide spray to the upper arm.
You could have debris stuck in the chopper blade area of the sump or a problem with the drain check valve that is causing your dishwasher to not clean well. I provided an image below that shows how to access this area of the dishwasher sump. Your dishwasher will look slightly different but the basic procedure is the same. Access the chopper blade area and check for a foreign object or debris that could be clogging the sump area. Check the drain check valve to make sure that it is operating properly. This will likely solve your problem.
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