Things You'll Need
Instructions
Turn the watch over to determine if the case back is a snap back or screw back. Most older watches, including most Wittnauer watches, are snap back cases. The case back will be smooth with a small notch on the side where a tool may be inserted.
Use a small tool with a flat blade, such as small standard screwdriver or a case knife, to loosen the case back at the notch and open the case back.
Look for a serial number stamped on the inner workings of the watch and write down this number.
Set the case back on the watch and line up the notch with the watch case. Press the case back gently with both thumbs into place.
Look up the serial number that was located inside the watch. There are several websites that offer manufacture charts that provide the corresponding date of the watch, including Pinnacle Supplies, Brittons Watches and The Watch Guy (see Resources).