britbrat- I don't have one in front of me and I don't have a steel memory so bear with me on this. Isn't there 2 screws on top? One w/o a spring that retains the barrel and the one with the spring for idle stop?

I honestly can't recall for sure but think I recall this.

Did some more digging:
http://www.osengines.com/parts/xr25681000.html

You can see they call it a rotor stop screw(idle stop). One screw, so I was wrong there. Screw does ALSO retain barrel in housng as it will come out if removed.

Still don't use for "idle" stop, use it for "KILL" stop