You might not think about maintenance when it comes to the dishwasher. If maintenance was done on a steady bases then 90 percent of the problems would never happen. Learn more about these basic things by continuing on. When your dishes are still dirty after running the dishwasher it means there is a problem. The spray arm more than likely needs cleaned. Turing the cap clockwise will loosen the arm so it can be lifted out. Spray it down really well and check it is clean, then put it back together. Remember overloading the appliance will also cause dishes to remain dirty. If you are not scraping off the dishes before loading this could cause things to be clogged.
On the tub there is going to be a float switch. Sometimes it gets stuck in the air. When this happens the tub will no longer fill correctly which means dirty dished. Make sure there is not any debris stuck around it and the switch is able to move up and down easily.
If you are still ending up with dirty dishes after the first two items are checked, then you are ready to tackle the valve screen. The first thing you will need to do is check how high the water is filling. Turn the dishwasher on and wait for it to fill with water, open the door and look at the water level. Is it at the heating element? If not then the water is low.
Kill the power and water to the dishwasher. The lower panels will need removed so you can properly disconnect the valve. Now within the body locate the valve screen, it will appear to be a wire screen. Clean it off then put everything back together. You just did dishwasher repairs Grove Park.