The best place to start would be a watch repair shop that specializes in old Pateks and/or women's watches. Do you have the broken mainspring? Just having the old one is probably enough for the right guy to find or make a new one that will suit. There are...
referring to the generous and glorious anglage combined with bridges not just striped but movement nomenclature and branding meticulously hand engraved. (a past vs present comparison not specific to patek tho)