Service IWC IW391023 – Restoration of an Anniversary Chronograph

Maintaining an IWC chronograph is not just a routine service task. It is a high-precision process that requires specialist knowledge, the right methodology, and a deep understanding of the company's mechanical architecture.

At The Watchmaker workshop, we recently undertook the complete servicing of a special model: the IWC IW391023, a limited edition "150 Years" anniversary model with a distinctive blue lacquered dial and classic chronograph aesthetics.

The initial situation

Upon receipt, the watch displayed:

• visible signs of daily use on the frame

• surface damage polishing

• need for complete mechanical service due to old lubricants

In chronograph mechanisms, proper lubrication is critical, as the complexity of the system increases the demands on precision and stability of operation.

The IWC calibre 79320

The IW391023 is equipped with the calibre 79320, an automatic chronograph based on the reliable Valjoux 7750 platform, adapted and adjusted to IWC Schaffhausen specifications.

Features:

• automatic winding system

• day-date display

• cam-operated chronograph architecture

• High reliability and easy maintenance when performed by a qualified technician

When disassembled, the movement reveals IWC's characteristic industrial yet meticulous finishing, with perlage and correctly finished bridges.

Service Procedure

The work included:

Complete disassembly

All components were removed, including the rotor, chronograph system, and balance assembly.

Cleaning

Use of multi-stage ultrasonic cleaning to remove old lubricants and microparticles.

Damage inspection

Inspection at:

• pivots

• jewels

• chronograph levers

• clutch components

Relubrication & assembly

Application of specialized lubricants at the correct friction points.

Adjustment

Fine regulation for optimization:

• amplitude

• beat error

• daily rate

Aesthetic restoration of the frame

The box showed signs of heavy use. With careful work:

• the polishing surfaces were restored

• the geometry of the lugs was maintained

• the design lines were protected

The goal was to restore without excessive removal of material.

The result

After service:

✔ Improved operational stability
✔ Correct chronograph operation
✔ Refreshed aesthetic appearance
✔ Complete restoration of user experience

The result once again embodies the character of an anniversary IWC chronograph, combining mechanical reliability and timeless aesthetics.