The pins at the back and front are the ones that hold the scales on. The pin near the center - close to the backbone (spline) - is the pivot pin. The pins that hold the scales on have a tiny diameter and are peened to form a head, keeping the scales tight to the frame. The pivot pin is rounded but does not have a head. To remove the scales, I ground down the peened heads on the front and back pins. I do this with a dremel rotary tool with a grinding stone attachment. To completely grind off the head you will cut into the original scales, and won't be able to salvage the old scales. Then I use a wood chisel to slip under the scale and pry it off. It comes off easily, and the shape of the chisel blade makes a perfect wedge to get it started. Note-be sure to use safety glasses when grinding on the pins. They are very hard and the grinding will send metel flakes into your eyes if you don't wear eye protection. I wear motorcycle goggles when grinding.