Whirlpool Upper Spray Arm not working

The upper arm of this diswasher does not rotate. I have taken all the parts inside the washer apart and cleaned them, also made sure there was nothing blocking the water tube to the arm. Water is reaching the arm but it’s not spinning. It spins freely by hand. Does the motor actually provide a pumping action for water to this arm, or should it move only using water pressure? I’m trying to figure out if I have a motor problem or soemthing else. Thank you.