Part numbers: Omega GF 620 spare parts catalogue and the 861 parts lists. Order of the chronograph works and hour recorder: Omega technical guide for calibres 860, 861, 910, 930 (1970). The guide leaves the basic movement and keyless works to normal bench order. Numbers stamped on the parts are teaching labels; real 861 parts are not marked with them. Parts are drawn for teaching from the 861 film drawings, not to scale. Right-drag or two fingers to look around. T shows the tray. F is full screen.

THE BENCH

A full service on a vintage Omega Speedmaster calibre 861, from dial off: the hour recorder and the chronograph works come apart in the order printed in Omega’s own guide, with the dial side, escapement and movement side, into four trays. Then it all goes back, last out first in. Every part with its number.

Learn shows every part, tool and number. Practise asks you to name the next part before it moves. Rounds after the first are Practise. Numbers stamped on the parts are teaching labels, not factory marks.

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