WS 7: Vintage Omega Seamaster Gasket Ring Replacement

The Movement, Cal. 552 (related to 551, no "buttelin"!)

The serial number of 22'xxx'xxx dates the year of production of this Omega around 1965 (source: Cooksey Shugart's Complete Price Guide to Watches 2001). And between 1966 and 1968 according to another Omega source (Kreuzer, see below). The caliber 552 is very similar to the caliber 551 introduced in 1959. The main difference is, that the 551 holds an exclusive C.O.S.C for the Constellation market introduction. Like the 551, the 552 features a beautiful swan neck regulator, 24 jewels, great bi-directional winding, plain Glucydur balance, 19'800 bph, first flexible spring block for easier regulation, power reserve over 50 hours due to a main spring with 7 evolutions (source: Omega Designs by Anton Kreuzer)
The proof reading and translation from German to English of the Book "Omega Designs" was obviously done in a hurry, "buttelin" should be bulletin and refers to the C.O.S.C. certificate from Neuchâtel, Switzerland also known as "The Observatory", Besides timing contests, the "Obervatoire" (French spelling) is certifying the accuracy of watch calibers in different positions and during different temperatures. Today many watches are mounted in a rack, then digital pictures record the position of the second hands. See a sample of a C.O.S.C certificate here. The cost of the certification are ca. USD 52 (late 90ies) and due to dropping and tighter margins, many watch manufacturers can not afford to certify their calibers anymore. USD 50 for the certification will have an impact of USD 300 (rule of thumb) on the price tag. C.O.S.C. stands for "Official Swiss Chronometer Control" and Chronometer is nothing else then watch, from Greek "chronos" (time) and "meter " (measure). The original French name is "Contrôle Officiel Suisse des Chronomètres". Still, I recommend "Omega Designs" by Anton Kreuzer for the Omega collector because it contains pictures of many rare Omega designs.

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FAB. SUISSE stands for "Manufactured in Switzerland" (French fabrique), ACIER INOXYDABLE stands for stainless steel -
Movement shows some marks from rotor play

The watch obviously has a service history. I am not sure how to interpret the engraved "1956" since Shugart's estimate production year of the serial number of the movement is ca. 1965 or ca. 1966 to 1968 according to A. Kreuzer. It is of course possible that this was one of the very first Seamaster watch cases issued in 1956. Omega would probably know when exactly the case with the serial number 166.002 was manufactured.  Important is, that it is a genuine Omega case back