Short Round:  Taking your 1901 sight off of your barrel and soaking it in some Hoppe's #9 or Kerosene should loosen up old dried grease, grime, and rust.  Using your clock face reference, pushing the lever toward 12 o'clock locks the sight to the base.  Pushing the lever toward 9 o'clock, releases the cam pressure and allows the sight to pivot on the base and front sight screw.

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