dishwasher not cleaning--how do I know if need new dishwasher?

we have a 15 year old Kitchenaid dishwasher. Lately it has not removed all of the food deposits on dishes & silverware. we have set to maximum water heat. living in Calif. we no longer use dishwasher detergent that contains phosphates.
is there any method for determining if the problem is with the dishwasher itself, meaning need new one, OR, problem caused by change in detergent components.
second question, is there a dishwasher detergent without the Calif. banned phosphates that cleans as well as phosphate containing detergent?
all replies welcomed! Aaron in N. Hollywood
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On 10/20/11 12:15 AM, snipped-for-privacy@pacbell.net wrote:

After the dishwater fills, shut it off and open it. The water level should be at or near the heating coil. If it's not, you could have a clogged inlet screen, a bad inlet valve, or a sticky float.
Finish Quantum has a good reputation. Other Finish products may not be as good.
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responding to http://www.homeownershub.com/cleaning/dishwasher-not-cleaning-how-do-i-know-if-need-new-dishwashe-11317-.htm clint73 wrote:
Be sure a clean the circular filter screen just below the lower water nozzle arm.. It snaps out for cleaning. Also, make sure both the upper and lower water nozzle arms are spinning freely.
------------------------------------- Clint.. Kent, Wa.
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