A professional who alters weight of watch balance wheels to correct timing of movement, using jeweler's tools and loupe. Responsibilities include:

• Receives movement from timing inspector with indication of rate of gain or loss in time.
• Replaces balance wheel screw with one of heavier weight or adds washer of specified weight when movement is fast, using screwdriver.
• Repeats operation on opposite side of balance wheel to maintain poise. Replaces balance wheel or files angle of screw point to reduced weight, using hand file.
• Repeats operation on opposite side of wheel to maintain poise.
• Observes minute parts, using loupe.