A professional who assembles, tests, and adjusts marine chronometers, using watchmaker's tools and loupe. Responsibilities include:

• Assembles parts, such as plates, bridges, train wheels, mainspring, and fusee, in specified sequence, using tweezers and watchmaker's tools.
• Greases and assembles fusee and barrel assembly.
• Tests assembled parts, such as fusee and barrel and train wheels for specified endshake (vertical movement), using tweezers.
• Bends parts, such as bridges, to correct insufficient or excessive endshake.
• Oils and greases bushings and other surfaces requiring lubrication.
• Cleans parts, such as plates, mainspring barrel, and hands, using buff stick moistened with benzine.
• Tests operation and fit of parts and subassemblies during assembly and makes adjustments to eliminate any improper fit or malfunctioning.
• Changes timing weights on balance wheel to correct deficient timing and tightens or replaces loose jewels, using watchmaker's tools.