I'm an accuracy freak, I set my watches to the second, I can't stand a watch that runs erratically, and I want to know if I made a good purchase and if my watches are healthy or need a service.
Today I test a 30+ year-old Zenith Chronometer-grade watch that has gone through one service 3 years ago. Let's see if it still matches COSC standards!!!
![](https://i.ytimg.com/vi/NQABKST94I0/maxresdefault.jpg)