Ok. He gave up and sent me the watch. Mystery solved. I never would have guessed. Peseux 170. He needs a staff. I have a 190. The book says the balance is the same. Do I sacrifice my parts watch for my friend? Do I swap it out for him? <sigh>
Sadly, I'm not a watchmaker. Balance staff complete only 😀
I've never replaced just the staff successfully. Not my watch and god knows, he's not paying me.