Dishwasher pump caviation

Question

A few months ago I urchased a GE dishwasher. Installed and it seemed to workfine. Reently it has not been getting dishes clean and in the last couple days has not washed dishes at all. When I run it through a cycle, I here a cavatation noise coming from the pump.I pulled it out last night and checked the inlet screen on the unit and it was relatively clean. Reinstalled and ran a cycle. Once again got the cavataion noise. Also notices that the upper rotary arms were not moving. So i added additional water to the unit and ran again and found that the arms rotated as they should.It seems that the unit is not filling with enough water for it to function properly.What is the water psi to be at to fill the unit?What is the timing cycle for the water valve to be open?Any ideas as to the cause?GLD5900N00BB s/n MM833534BthanksDon Filippelli