Buy a new dishwasher. I had an insidious dishwasher that went through its entire cycle, but sometimes refused to make things clean. After weeks of trial and error and a few new parts, I finally determined the control board was popping all the detergent into the tub after just a few minutes in the first cycle and then draining and restarting the main cycle with just water. Everything mechanical was working perfectly, but it was literally being stupid at its job. I just couldn't trust it to not do that again, and decided to scrap it and upgrade on a Black Friday sale.