Service: Omega Seamaster Professional co-axial GMT calibre 2628B

IMG_1903When Omega started out on the adventure that is the co-axial escapement, they embarked Β on a bit of a journey. The main advantage of the co-axial escapement invented by George Daniels is that it doesn’t need any oil. The locking and acceleration of the balance are done by different stones against different wheels. That is the theory. When Omega made their first movement with the co-axial escapement, they noticed that the teeth of the escape wheel that locks could deform, so they added a tiny amount of oil there to dampen the blow when the pallet stone locks the wheel.

A shame really, and they have gotten rid of this design flaw in their newer movements.Adrian sent in this Seamaster GMT, as it just stops after a few ticks.IMG_1904

The watch has a crystal case back so you can see the movement. On first sight, it looks exactly like the ETA2892-A2, and there is a good reason for that, as that is the base of this co-axial movement.IMG_1909So far, it looks exactly like the ETA it is based on.399-01

Here lies the difference – the co-axial escapement.IMG_1915The wheels of the wheel train.IMG_1918

The barrel bridge.IMG_1924

The bottom plate. The GMT version has an intermediate plate, making additional room for the GMT feature.IMG_1931

Below that plate lurks the date change mechanism, and the wheel providing the GMT functionality. As a sacrifice, there is no quick-set date.IMG_1935

And off into the cleaning machine…IMG_2038

Ready for reassembly.IMG_2039

I start off with a new original Omega mainspring.IMG_2042

Now the wheel train goes in.399-02

The spot you have to oil to dampen the shock from the pallet stone locking needs a very very tiny drop of HP 1300, and I have a 2ml bottle of the stuff which I won’t be able to use up until it expires in March 2019 πŸ˜‰IMG_2044

Now the balance can go in, and the movement starts ticking.IMG_2046

My timegrapher has a special setting for this movement (Spe1), and I adjust the lift angle to 38 degrees, and I get a very nice graph indeed. Bingo.IMG_2048

Now I turn my attention to the bottom plate.IMG_2052

The dial and hands go back on.IMG_2054

I case the movement, put the auto winder assembly back in, and put new gaskets into the case.IMG_2056

I waterproof test, and all is well.

19 thoughts on “Service: Omega Seamaster Professional co-axial GMT calibre 2628B

  1. Hi – I have this very same watch which I purchased from new when the Co-Axial GMT first came out with the crystal glass back. I could do with a service and I wonder can you do this for me, or point me to someone that can. and what would you be likely to charge?

  2. Christian,
    I cant get my bullhead crown to screw down, it does not seem to be able to catch the threads? Also when i leave my omega off after a few hours the minute and hour hands stop, but the second hands carries on working, is this normal?
    Many thanks

      • Many thanks for the help christian, when i bought it i was told it had just had a full service, it came with a full years warranty, i will take it back and explain the problem.

  3. Hi, I have just acquired an identical watch, which is losing 6 second per day after just being serviced, can this be improved upon?

    • Your movement is COSC certified, so it should run within the COSC specifications – being -4 to +6s/day. I’m sure that whoever serviced it will be happy to re-adjust the movement.

      Best regards,


  4. Hi, I have just acquired an identical a seamaster gmt, and it is losing around 5-6 seconds per day, despite having just been serviced. Is this within guidelines?

  5. Hi,
    I have an Omega Seamaster Professional with a Co-axial movement. How can I tell if the movement it has is the old and defective one, or the new one?


  6. Hi Christian. ETA now recommend the use of Moebius HP 1300 for many lubrication points on the 2824-2 movement, and possibly many other movements also, That should help to get it used up before 2019.

  7. Hi Christian. Many thanks for allowing me to actually see what you did to get my Seamaster functioning again. I really love this design, although truth be told, I prefer my Speedmaster (which has had the ‘Christian touch’ and is back to 100%)
    If I get a Daytona (if if if) I’ll let you loose on it too!
    Love to T and the sprogs,

  8. I think my next major purchase will be a Seamaster! Just an iconic classic watch, I think most collectors would want at least one in their collection!

  9. Design flaw or not I love the modern Seamaster – they look great πŸ˜‰

    Can whatever the fix is in the later versions of the movement be retro-fitted to the older ones?

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