I've had this thing forever [B&S No. 13 0-1"], and for whatever reason decided to strip it down and get it back working this weekend. Guess I had too much free time. It's clean now but needs to be reset, only I can't figure it. This mic has some age on it and doesn't seem to adjust like newer models. There is a very small hole on the thimble, between the grip and the ratcheting screw at the very end. I'm guessing it takes a special single-prong spanner (that I ain't got) to adjust. Not too much info on these that I've found so far. Help?