Repairing a worn Microtor – from calibers 215-218-68-69

A quick how-to guide on repairing a worn out Polerouter Microtor automatic winding system.

Repairing a worn Microtor – from calibers 215-218-68-69

The Universal Geneve Microtor calibers were some of the most advanced watch movements of their time. They paved the way for some of the thinnest mechanical watches ever made, by integrating the winding rotor into the space of the main mechanism rather than sitting over the top of the movement.

Incremental improvements to these revolutionary winding systems led to horological patent after patent being filed, and Microtors are an integral component in some of the highest quality timepieces being made today. A UG Microtor caliber in good condition is drop-dead gorgeous, a combination of the Côtes de Genève finish on the plate and mix of steel, gold, and ruby colours.

That said, these movements are now over 50 years old and as one might expect, many seem to have seen some real battles during their time. Heavily worn parts can render some components completely non-functional, including the automatic winding system. The microtor system itself is prone to wear over time, eventually manifesting itself in the form of an unflattering scraping sound, and leaving circular “rotor scars” on both the rotor and the caseback (below).

All is not lost if your Polerouter has a worn rotor – they are, after all, an assembly of mechanical parts which can be replaced and restored. The parts that will require replacing, and the method of replacement, will vary according to the caliber.

There were two main rotor types utilised in Polerouters:

  • Type 1Stem/Axel rotation: calibers 215, 215-1, 215-2, 215-9, 218-2, 218-9 (and US-market low jewel equivalents); and
  • Type 2Bearing rotation: calibers 68, 69, 1-68, 1-69.

This list does not include the calibers 71 and 72, though they also utilised a (different) bearing style rotor system.

From the UG Technical manuals, we can see the individual parts which make up each type – the top image is for Type 1, and the bottom image is for Type 2.

Below we have the technical construction of the Type 1 rotor.

In this instance, it is not the rotor weight itself that typically wears out, but rather the top of the stem/axel around with the rotor oscillates – part number 1496. The equivalent piece for the Type 2 rotors is part number 1497, which is a complete bearing unit that performs the same function.

Its these two parts which are most often are the cause of an underperforming rotor winding system: 1496 (oscillating weight axel) for the type 1 rotors, and 1497 (oscillating weight bearing) for the later type 2 rotors. In my experience, replacing these parts is the solution for 90% of cases. Keeping in mind, that even NOS parts are 50-60 years old, and may have oxidised or no longer be functional. Additionally, it is important to remember that the early type 1 rotor requires lubrication according to page 8 of this industry article. If the golden coating of the rotor (oscillating weight) itself has worn away, it can be replaced with part number 1143/1 (type 1) or 1143 (type 2). The type 2 rotor weight is purely a weight, whereas the type 1 weight is jewelled, so replacement of these are usually only for aesthetic reasons, and will only rarely affect performance.

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