A professional who attaches balance assembly to balance bridge. Responsibilities include:

• Positions regulator in nest of holding block and places balance bridge over regulator to fit balance bridge jewel into hole in regulator.
• Presses bridge into place, using tweezers.
• Positions balance wheel and hairspring assembly over bridge, and places hairspring stud into hole in bridge.
• Tightens screw to hold stud securely.
• Oils balance bridge jewel, using oil-filled hypodermic needle.
• Observes minute parts, using tweezers and loupe.