Just a thought, when you get the scales off, you could try cutting a groove on the inside of the scale along the crack with a small burr on a dremel tool, then fill the groove with super glue (use the gel type) then sprinkle baking soda on top of the glue. The baking soda makes the glue dry almost instantly and will fill the groove with a hard almost glass-like substance, let it cure and sand it flat again.
Just a thought!