olBEAR - I have a 1901 sight that needed the Leaf straightened. I took it apart in order to answer your question.

(note - Before disassembly, I scribed a hidden index mark on the slotted head of the 'binding-screw' and the bottom of the sight-base. The 'Binding Lever' is timed and the screw head has a curve to match the barrel radius. This aided putting things back together properly).

FWIW - My leaf spring could be removed from its dovetail in the 'pivoting upper-base' with very little effort. I used the tip of a Punch, slightly inserted in the hole through the spring, to pull the spring reward out of the base.

You may need to clean debris or burrs from the dovetail of the base. It would do no harm to file or stone roughness or burrs off the dovetailed edges of the leaf spring. These parts should slide together with only minor effort.

Also note, my 1901 sight has a second folded flat spring that is held to the upper base by a screw that goes through the hole in the leaf spring.

The purpose of this folded flat spring is to maintain a slight tension on the upper base when the clamping lever is released. This feature was not found on early version of 1901 sight. It is nice for operation, but, not indispensable.

Also, there is a thick washer that fits into recesses machined in the upper and lower bases. This serves as a pivot for the upper base.

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