G.P.: Watches just had to work properly, so that when they wear off, they could be sent to an atelier, where specialists repaired the internal mechanical parts and added a new case, hands and straps.
RBTH: Why not use the new parts instead?
G.P.: They were expensive to produce and factories were not always good at it. That's why they mass produced the so called 'clearance kits' that consisted of a new case, leather straps, the hands of a watch and a clock winder.
RBTH: So you could just find an atelier, give a master your old watch and get one that looked like new, but with the same used and repaired parts inside?
G.P.: You also had to pay a little bit, but compared to the price of a new watch, it was chicken feed.