HiCustomer

If the dishwasher have been used constantly throughout its nine years of life then the problem is likely related to the long service time of the appliance.

First check if the problem is in effect only the lower arm. Sometimes the problem is more evident in the lower basket where dishes and pans are placed. Put the dishwasher in a rinse program. While the cycle is on open the door and try to see if the bottom arm was rotating and spraying. If the bottom arm is not working properly it is either blockage inside the arm, an internal leak that cause the arm loosing pressure, or the diverter valve built in the pump that switches flow between top and bottom arm is defective (depending on the model).

If problem is not only the lower arm, then the recirculation pump may have lost power because of debris accumulating inside the pump. The pump can be removed and disassembled to get rid of the blockage or replaced. The pump is located at the base. Here an exploded view showing the parts inside the pump:



Before going for the pump there are other problems that may result in dirty dishes.

Make sure that you are using the proper detergent and that the detergent drawer is opening and releasing the detergent.
Pressure from the house and inlet hose at the back must be checked. If the machine is underfilling, that is the reason for the problem.
Check that water is heating up correctly. A defective thermostat or element may result in insufficient water heating and dirty dishes.