Leaf Blowers

I have a 580BFS blower and when I removed the switch/throttle cover on it a little black piece fell out and I can't figure out where it goes. When I look this piece up in the IPL it's called a "stopper" and has part number 576 56 28-01. See attached photo where I have the part in question circled. Anyway, my question is, where in the heck does it go and what purpose does it serve? The blower works fine without it but it has to have a reason for being. If anybody can take a photo of it in it's proper position that would be GREAT!

thanks in advance!
Paul