Thanks! That was, indeed, the problem. The screw was backed out at least an eighth of an inch from where it needed to be. The safety is now working correctly.

However, I now have a new question based on the instructions. I have another screw that is not shown in the pictures, or mentioned in the instructions. I've marked the location in red in the picture below.


[img width=505 height=450]http://i132.photobucket.com/albums/q35/ChromeLibrarian/3_parts_list.jpg[/img]


Any idea what this screw is for?