CleanSump
Site Donor 2022
Well, there's a certain expectation of Quality Control with a Mercedes dealer part and the OEM supplier is an important measure of that quality.I mean it’s just some seals and bearings no matter who makes the pump it should still be able to turn by hand.
And, the OP apparently hasn't replaced one before so he's making sure all is right. That's the point of this forum and a very appropriate thing to do.