The correct direction is to contact S&W about doing this. Because cutting the ratchet pawl is a task that requires the use of a very special tool (IIRC a Cutting Hand) that is inserted through the window for the hand and operated by hands with the skill to do this task quickly and easily.

As a result you need a tool that is never sold to the public and for which the detail drawings are most likely kept under lock and key. Then you have to have someone very skilled in this task train you how to do it and have enough disposable materials on hand to do enough practice to gain the skill to do it properly.