Water flow to my 7-year-old washer was really slow. We were getting the dreaded Whirlpool F20 code. Most washes wouldn't complete. By opening and removing the dispenser and then running a load, you can easily verify whether there is enough pressure to drop water in the correct dispenser compartments. The water in my washer was just dribbling in the back.
After replacing the water valve, water pressure was high and the washer works like new!