A professional who inspects assembled watch train (center, third, fourth, and escape wheels with pinions) for vertical play of wheels (endshake), meshing of gears, and cleanliness of movement, using watchmaker's tools and loupe. Responsibilities include:

• Moves wheels up and down to test endshake, using tweezers, and determining from experience whether shake is within acceptable limits.
• Turns center wheel to ascertain that gears mesh and that train turns easily.
• Examines assembly for cleanliness, oiling of cap jewels, and to determine that wheels are level and in parallel planes, using loupe.
• Rejects or accepts watch train assemblies and places defective assemblies in trays according to type of defect.