Finding The Serial Number
Click HERE for tips on how to open your watch.
YES
Movement serial numbers were unique factory-stamped numbers. They were not always sequential in order of manufacture by date.
NO
Cases also had unique factory serial numbers, but watch movements can be moved easily and quickly to different cases.
How To Open It
Threaded Covers
Both covers unscrew like a jar lid. Do not pry anything!
Hold the case in your left hand with your thumb against the pendant and rotate either cover counter-clockwise with your right hand. If they're stuck try using rubber kitchen gloves for a better grip, or putting it someplace warm to expand the metal.
Hinged Covers - Front
Open-face cases have a crystal set in the front cover, which opens on a visible hinge. These do require a certain amount of prying, and there will be a thumbnail catch or a small slot for a pocketknife blade. Hinged cases work on friction and if yours isn't too worn the cover will snap shut and stay closed.
Do not force the cover past 90 degrees!
Hinged Covers - Back
The back cover(s) open on hinges, which are usually visible. These also require a certain amount of prying, and there should also be another thumbnail catch or pocketknife blade slot. There may be a second inner dust cover, called a cuvette, that opens the same way.
Do not force the cover past 90 degrees!
Swing Cases
A swing case has no rear cover. Pop up the crown first before unscrewing the front bezel to reveal a hinge at the top of the dial near the pendant. Look for a thumbnail catch at 6:00 on the dial to help you swing the movement open on the hinged inner ring. If you feel resistance, stop to make sure that the crown is indeed up.
Hunting Cases
Press the crown should cause the front cover to open, unless the lift spring is broken. When closing the front do NOT click it shut! To close it, press the crown, close the front lid, and then release the crown. The steel latch is much harder than the gold-plated brass of the front cover, which will wear out some day.
Do not force the covers past 90 degrees!