Service: Omega Seamaster Cosmic calibre 565

IMG_6605Today, it’s a Seamaster Cosmic with the calibre 565 movement. Peter sent it in, as the female part of the winding stem is broken, and the crown fell off. The crystal is still half way decent, and he wants to keep it.

This is a monocoque type case, e.g. there is no removable case back, and entry is through the front. To remove the movement, you turn the movement until the 4 faces the winding stem, and you can take it out.


The jewels have caked-in oil and dirt in them, so I recommend a full service, and Peter goes along with that.


The balance jewels are dry as well – no oil left.IMG_6641

Balance and pallet fork removed, and the wheel and barrel bridges still in place.IMG_6645

The bottom plate.IMG_6647

Everything taken apart and ready for cleaning. Some of you might notice that I’ve bought a little basket for the very small parts, such as screws and jewels. Just to avoid anything slipping through the basket.IMG_6674

The new mainspring goes into the barrel.IMG_6675

I lift the wheel bridge into place.IMG_6677

The basic movement is back together and ticking.IMG_6678

Not fully wound, this is looking very good.IMG_6685

When assembling the bottom plate, I notice that the date doesn’t change. It wants to, put snaps back to the old date after having moved about half a day. This is the culprit. The date changer wheel has a little metal strip that engages with the date wheel. It has slipped back slightly, and I move it back into its original position and re-rivet it. If it slips back again, it will need replacing.IMG_6686

Casing the Cosmic movements is a bit tricky. You first have to make the final adjustment to the movement, then put the dial and hands on, put the second hand in place, which needs supporting the second hand arbor from the back, and then put the auto-winder on. Then the complete movement can be cased.IMG_6687

You can see that someone used polyWatch on the crystal. As Peter wants to keep it, that’s fine with me.

9 thoughts on “Service: Omega Seamaster Cosmic calibre 565

  1. Hello!
    Great article and information. I followed it step by step as i have had a similar project. I have just one issue though, i dont know how to put the crystal In again. Do i need the compression tool Or Can i do it with pressure? Thank You so much!

  2. Nice work. Maybe an odd question, but what alloy has been used for calibers like this one? Or is it brass plated or something like that?

    Many thanks!

  3. Hello,I have a omega sea master cosmic that is missing its crown as it fell out and I lost it.would you be able to repair and service this watch,if so how much would you charge,and what is the best way of getting the watch to you.
    Many thanks mark.

    • As a starting point, I suggest reading my FAQs, the price list, and the Contact page.

      That should answer most of your questions.

      Best regards,


  4. fascinating. have just bought one, and tho the day doesnt change ,(date does but at 6 ocloc approx, not midnight) i am not going to have these aspects attended to yet… great to see whats inside. thanks

  5. What a joy to see such care going into the repair and service of this watch. Particularly interested in the digital timing regulator. What is the tolerance of this watch’s timekeeping after service?
    Very intereting site, thank you.

    • The beat rate (=accuracy) of the watch differs with the position it’s in. You can’t really predict how accurate the watch will be when worn. For a vintage watch like yours, I’d expect an accuracy of +-20s/day, but, with a bit of luck, it will perform better. I set the watch in the workshop to close to 0s/day, erring a bit on the fast side – normally around +2s/day. That is of course in one position, and the rate will change slightly when you turn the watch.

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