Top sprayer arm won't spin

The top arm of my dishwasher will not move. It rotates freely when the dishwasher is off but remains stationary during the dishwasher cycle. How do I fix this?

Hi,

What is the water level in the dishwasher during the wash cycle?

Try to add 1/2 of gallon of water and see how it will work.

Here are the breakdown diagrams and http://www.appliancepartspros.com/parts-for-whirlpool-du948pwkb0.html

Gene.

Are the dishes clean

The dishes are not coming clean on the top rack, in fact, they are dirtier coming out than going in, except right along the stationary spinner arm. I have tried adding water with no different results. I have tested the water inlet valve for electrical continuity. The float appears to be working correctly. I have tried Dishwasher Magic to reduce the food particles. The water temperature is plenty hot. Anxiously awaiting a possible solution. What is the expected life span of this dishwasher? Thanks for your help.

Make sure the upper spray arm manifold (#11 at the [B]diagram[/B] is in place and is properly connects to the water outlet.

Remove the upper dish rack and the water supply tube. Remove the pump outlet (#14 at the [URL="http://www.appliancepartspros.com/pump-motor-parts-for-whirlpool-du948pwkb0.html)) and check the impellers.

Gene.