One of the two knobs I ordered turned out to be defective in that it will not screw down tightly on the screw provided... there is a 1/4-inch gap when it simply stops. The good news is, customer service is sending me a new knob right away, at no charge, and without my having to return the original knob! I just hate to throw out such a nice knob, but what is one to do with one that cannot be seated properly?