S.,
Did you check to see if something fell into the bottom and may be blocking the arm from turning? Give the spray arm a good spin. How is the water pressure? Is the drain hose properly installed? It should go out and make a loop up and over and into the drain or garbage disposal and be higher than the level of the exit drain hole, to prevent backups. Just a few suggestions to check- or maybe it's just time for a new dishwasher ;-). Also, did you know that the government outlawed phosphates in Laundry products, but allows them in dishwasher detergents? Brilliant, huh? Shaklee makes an awesome dishwasher powder without phosphates or chlorine. It is enzymes, eco-friendly, and my dishes sparkle! It also won't etch your glassware! Give me a holler if I can help.
Take care,
M.