while i can't speak specifically to what zenith does to vintage watches. . it is a good rule of thumb to NEVER send any vintage watch back to the manufacturer. ever.
find a good independent watchmaker who knows the brand and can source zenith parts
You would need to provide VERY strict instructions about what you want done and be very clear about anything that you DON'T want done. I have sent 2 watches that were sent through to LVMH in Switzerland, for work that could not be done in Canada and one was great and the other had an issue that I paid my local watchmaker to fix. It was relatively minor, albeit irritating, but it was easier than sending it away again.
There are 2 independent watchmakers in my vicinity who are very good with Zenith chronographs. I have the same dilemma right now with an El Primero Rainbow from 1993. The crown threads are quite worn and my watchmakers can easily service the movement but they cannot get a replacement tube and crown. I could probably get by, if I am super careful and don’t over tighten the crown but it only engages the threads for 3/4 of a turn.
If yours has no issues and just needs a service, a good independent watchmaker would be the best way to go.
Eventually, they would also gladly ruin it. Send it to an independant watchmaker. If you can share your location, I’m sure some members will be glad to recommend you good craftsman.
Nice watch btw 😉
That's a fantastic piece. I would have a local competent watchmaker do it. Unfortunately for many, the "trust" factor is not there when it comes to a factory service for a vintage piece by Swiss brands. It's based on many shared experiences by watch collectors.
I agree with all the advise on an independent (we have to support the dying trade), but like the aforementioned Rainbow crown tube, how is one to get parts? Same issue with Rolex or Omega, the companies keep a very strict hold on parts distribution. Are there independent Zenith account holding watchmakers? I am genuinely curious as a Rainbow has always been on my short list but the idea of only being able to send it back to Zenith if I run into a serious issue is enough to make be balk.
If you sending your watch to Zenith in Switzerland prepare to pay huge premium once I send my Zenith Defy and they wanted to charge me 1700CHF for full service.
After a lot of discussing with them they agree to a small service where they`ve done all with the exception of servicing the movement which was done by my trusted watchmacher.