Quoted from vid1900:In your goody bag, you got a little Gap Tool (sometimes called a fork or by Williams official name "Flipper shaft end play spacing gauge"). Many people do not even know why they have it.
I'm not sure anyone sells them anymore, but the Williams part number was 03-8194.
Only place I know of Vid:
http://www.dmspinballs.com/flipper.html flipgau.jpg