The spanner isn't needed to break off (as designed) the adjustment screw. You do that with the adjustment screw and an appropriately sized screwdriver. You turn it counter-clockwise.

The spanner makes is easier to put the nut on and thread it in. I found it of little use, I just used my tweezers.

The suggestion to view the on-line video is a good one. Click Here for Midway's Video

I got some new ones right from S&W last month. I was very disappointed because the white outlines were not as crisp as my older ones and one of them wasn't even straight. Still, I prefer the WO over the all black.