Hi according to convention when the balance is at rest the terminal curve should rest in the center between the boot and the pin. As you said you should be able to run the regulator arm from + to - without .interfering with the spring If the spring rests on one pin or the other it will affect the swing of balance and the rate Itshould beat evenly between the pins..
So, I decided to tighten the cannon pinion using my Seitz jewelling tool (which I had never done before) and it was a pretty smooth operation. I tightened it about 0.015mm and it felt pretty perfect after this.
However, I ran into more serious problems as I noticed that the amplitude was seriously off. So, I've decided to start a new thread to address my amplitude problem and if you are interested and/or perhaps can provide me with some advice, please go to this thread: Need help with Unitas 6325 amplitude problem.