A mechanical watch measures the passage of time by using mechanical actions and energy from an internal spring. Time is also regulated by a tiny set of gears which aid in keeping the correct time. Mechanical watches may sometimes break or must be set backward or forward, like during Daylight Saving Time. It is recommended that expensive mechanical watches be regulated by a professional, but it is less expensive to learn how to regulate a mechanical watch yourself.
Use the watch screw driver to carefully and slowly unscrew the screws on the back of the watch case. This step needs to be performed carefully as to not lose any small screws.
Set the screws aside for later use, or until after the regulation has been made.
Pry open the back of the case with the case knife. Do this carefully as well, as to not lose any parts inside of the watch which might be positioned loosely.
Place the case aside and place some masking tape or other thin covering over the case back for protection.
Find the +/- symbols on the back of the watch.
Locate the regulator bar which is directly in front of the +/- symbols.
Move the regulator bar very slowly in a clockwise direction to slow the mechanical watch. To speed up the clock, move the bar counterclockwise. This can be done with a toothpick for better handling.
Place the case back onto the watch and secure with the screws.
Let the watch run for a day or longer to see how it is running. If it is too slow or too fast, repeating the steps is advised.
Moving the regulator bar should be done very slowly, as the bar is sensitive and will create a massive change in watch speed if not handled properly. If problems continue to persist, or if a watch is too valuable to be opening yourself, consider taking the mechanical watch to a watch mender. You can purchase a watch repair kit at watch and clock stores, or over the Internet, which include the necessary tools to regulate a mechanical watch.
Be careful to not lose the screws from the back of the watch. Purchase additional watch screws if necessary.