A note on sources. Every guide here is built from Omega's own manuals, Omega-qualified watchmakers writing on Omega Forums, and the established collector press — Fratello, Hodinkee, WatchGecko. Where sources disagree, we say so. Where the collector consensus is "leave it alone," we say that too.
None of this is a substitute for a watchmaker's bench. When in doubt, ask one — preferably before the crown starts feeling crunchy.