Electrolux ELFW7637 loud pump

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This is mostly academic since the big box store has agreed to swap it out, but I'm curious in case its replacement behaves similarly as there are few options for Electrolux service out here.  The problem is more or less as described.  At a few points throughout the wash cycle it makes a continuous, loud humming noise.  If I didn't know any better I'd say that a (the?) motor driving one of the pumps is stalled out.  I ran it through the diagnostic tests and everything was nice and quiet as I'd expect.  The detergent divot filled with water, the heater was silent, the drum seems balanced and quiet all the way up to 1300 RPM, all the pumps made reasonably quiet noises. All of that makes me think that there's nothing wrong with the pump or its motor.  With that in mind I ran the number 10 (concentrate wash pump) test after draining the tub and got exactly the loud noise I'd experienced.

So from my end it seems like the washer is running the detergent pump dry.  I'm coming from an old Whirlpool direct drive washer so maybe my expectations are too high.  Is this normal? And if so, should I expect it to make a racket?  If that's not normal behavior, what could the problem be?