** It turned out to be the fan on the motor/pump assembly came loose and made a whirring sound. The fix involved replacing the entire pump/motor assembly as it was a "unitized" assembly. **
GE's dishwasher pump design was famous for that, the fan breaking loose from the motor shaft and grinding against the motor's housing. Since the motor was welded together and not able to the taken apart, it had to be replaced. Now you can't even get just a replacement motor but have to replace the whole pump and motor assembly (which is now actually a much better design).