Another disappointment with buying an "Open Box" item.  Wayfair assured me they check all returns to ensure they work properly.   Well, they couldn't have checked this, because there wasn't enough room to pump,  it was defective.    They finally agreed to give me a discount, but tried to say it is sales final -- but again I had to argue that I expect something to work properly otherwise I would not have bought it.  No-one knowingly buys a defective product -- what's the point?