How to fit an hairspring when I've no mark on the balance to align the stud ?

[richiesgr]

Hi,

I get a citizen without hairspring I managed to find a new one but there is no mark on the balance to align the stud on the balance how can I find where the put the hairspring ?

Thanks for any help 

[JohnR725]

put the balance wheel in the watch without the hairspring. Rotate the balance wheel until the watches in beat. then from the center of the balance jewel assembly visualize a line going through the stud holder continuing until the rim of the balance wheel and put a Mark there. a felt pen works really well as it's not permanent.