Whirlpool GU2300XTS started making a whining noise during the wash & rinse cycle a couple weeks ago. Seems to wash and run through all of the cycles properly. I opened up the sump and checked the pump inlet for obstructions, etc, but all looks okay. Still makes the "whining" noise with spray arms removed. I suspected the motor or pump but then noticed that when you press the "cancel-drain" button that all of the water from the basin pumps into the disposal fine but there is no noise, absolutely quiet when it's draining. Now I don't know what the difference is from when the motor/pump is running during the wash & rinse cycles vs the drain cycle, that would make the noise. Motor capacitor? Pump drain solenoid?, Check valve? Any suggestions appreciated. Thanks.

Thanks for the help Gene. I ordered the assembly.