Correctly servicing a mechanical watch means dismantling the entire movement of the timepiece, giving each part a bath and making necessary repairs. Most of the work consists of completely disassembling the movement and then putting it back together. A movement is the spring-loaded mechanism, or engine, that powers and regulates the watch. Most mechanical manual wind watches are pre-1970 timepieces, but many contemporary watchmakers continue to produce automatic mechanical models. Servicing manual winds and automatics requires the same cleaning steps. Novice mechanical watch owners should take a watchmaking class online or at a community college before tackling the project.
Pry open the snap case back of a mechanical watch with a thin blade. Twist the screw-down case back counterclockwise with the palm of your hand and remove it from the case. Remove the rubberised gasket sealing the case back to the case.
Wind down the mainspring, which is a tightly wound strip of steel in the mainspring barrel, by using a screwdriver to push aside the stopper found on the stem connected to the crown. The stopper is a tiny nub on the stem. The stopper passes over the mainspring gear when rotating the crown. Lifting the stopper unwinds the mainspring.
Use a screwdriver to remove the two small screws that attach the movement to the case. Place the screws in a compartment of an egg carton. Remove the movement from the watch case. The watch is now in three parts: movement with dial attached, case and case back.
Remove the hour/minute hands from the dial with the hands remover tool. Place the tool directly over the dial’s centre post. Set the feet of the hands-grabber over the post and gently pull the hands from the post. Unfasten with a screwdriver the two screws that hold the movement and dial together. Remove the dial from the movement.
Break down the movement by removing the hour wheel and gear with tweezers. Refer to the diagram to identify these parts. Remove the cannon pinion with needle-nose pliers. The cannon pinion is a small gear mounted on a shaft. Unfasten the bridge by removing the screws that allow it to contain the gears and mainspring. Locate and remove the balance wheel from the bridge. Remove with tweezers the jewels, which could be as many as 25, from their holes. Remember to place each part in a separate egg container compartment. The jewels, which are synthetic gems that help lubricate parts, go in one compartment.
Fill shot glasses with naphtha and place each part, except the mainspring, dial and hands, in separate glasses. Use lint-free, absorbent paper to dry each part. Place a drop of watch lubricant in each jewel hole. Replace the mainspring with a new one. Use a Q-tip soaked in warm, soapy dishwater to wash the dial and hands. Inspect each part for wear, bends or cracks. Replace parts if necessary. Replace the existing gasket with a new one.
Rebuild the timepiece in reverse order of disassembly. Set the time and wind it.
Take a watchmaking course and practice on a junked watch before servicing a watch you plan to wear.
Never force parts from the watch. They can break.