Repairing a Swiss watch is no different than repairing an American or Japanese watch. All watches---whether mechanical hand wind, automatic or quartz-powered---essentially feature the same parts. Repairing crystals (the glass protecting the dial) and watchbands, and replacing batteries are simple tasks. Repairing the mechanical movement, which is the spring-loaded motor that runs and regulates the timepiece, require training and a level of skill. Minor repairs on vintage watches manufactured before 1980 are relatively easy to perform. Only experienced watchmakers should perform repairs on contemporary post-1980 timepieces. Most nonfunctioning watches don't need repair but only needs to have the movement cleaned.
Inspect the crystal for minor nicks and scratches with a jeweller's loupe or magnifying glass. Replace the crystal, which is made of acrylic on vintage watches, if the scratches are deep. Have a watchmaker replace a damaged sapphire crystal.
Apply a dab of Brasso or similar polishing compound to the surface of the crystal. You do not have to remove the crystal from the watch. You may also use toothpaste as a substitute. Like Brasso, it has abrasive qualities.
Use a toothbrush or clean cloth to apply the polish to the crystal. Rub gently in a circular motion for about five minutes. Wipe clean with a cloth and repeat. Surface scratches should be removed.
Place your fingertips around the bezel of a vintage Swiss watch. The bezel is the outer ring securing the crystal. Rotate the bezel counterclockwise with your fingertips until it is free from the watch case. Use a rubber jar opener to twist off a stubborn bezel. Free the bezel from the watch case.
Insert a case blade or fingernail under the crystal and lift it from the watch case. The crystal on vintage watches may be fastened to the case with plastic or rubber cement. Wiggle the crystal from the case with your fingertips.
Use a brush with a squeeze bulb to brush/blow away dirt and dust from the dial. For stubborn grime, use a cotton swab dipped in warm dish soap to gently clean the dial. Keep in mind moisture damage may occur on old painted dials if care is not taken.
Return the crystal to the watch case. There is no need to use rubber cement or glue to fasten it to the case. Screw down the replacement bezel onto the case with your fingertips. Hand-tighten the bezel and ensure it's snug and the crystal is flush with the case.
Open the case back of a vintage mechanical Swiss watch with a case blade. Release the tension in the mainspring, which is a wound-up ribbon of metal in the mainspring barrel, using a toothpick to push away the stopper. The stopper is a small notch on the stem that is connected to the crown (winding nub at 3 o'clock) to wind the watch.
Remove the two tiny screws that fasten the movement to the watch case with a screwdriver. Take out the movement.
Use tweezers to remove the mainspring from the barrel. Replace the mainspring. Replace the movement in the case and fasten with the screws. Replace the case back and wind the watch.
Most watch malfunctions occur due to a dirty or dry watch movement. This means the watch is not broken but that it needs cleaning. Repairing or cleaning movement is not for novice hobbyists. Take a community college, vocational or online watchmaking course before tackling complex repairs.
Limit repairs to minor tasks on vintage watches. Contemporary watches need special tools and are too complex to disassemble and assemble without experience and skill.