Mine(Model-LDS4821ST) did the same thing! This is what worked for me- I was very, very lucky. It turns out it was the check valve. Appliance parts pro AP4442609/ 5520ED4004A- I also replaced the Pump gasket- 5520ED4004A. Did a full run and it was quiet again. Will continue to run it and report back. Also the way I proved out that it was not the circulation pump, was to attach a drill to the motor shaft and ran it forwards and backwards many times. There was not any bearing noise or bearing wobble. All was done from inside or dishwasher with unit still under the counter . Good luck to all.