dishwasher not cleaning

We have a GE Energy Star with the ExtraClean Sensor. The repairman has replaced an arm that was not spinning, but the problem of "not clean" dishes is not solved. Also, some detergent remains in the detergent compartment after the cycles are complete. Mr. Repairman charged us $75 and appears to be out of ideas. Do you have any?
Thanks.
Chris Toews