This Rolex Datejust was suffering with a common fault that Rolex’s often develop – a worn rotor post. The watch was losing time, and I could tell straight away from the sound within the watch, the rotor was loose and touching the case back.
On the newer Rolex calibres, they have reverted to ball bearings for the rotor to pivot on, as opposed to a post. Calibres such as the popular ETA 2824s and 2892s use bearings very successfully, they do suffer from wear and occasionally need to be replaced, but not nearly as often as a rotor post on a Rolex. Its down to the weight of the rotor, with bearings its evenly distributed across a number of ball bearings, with a rotor post, the force is centralised on the one post and wear occurs at a faster rate.
Case back off revealing the Rolex 3135 calibre. Not too much amiss at this point, but I am able to confirm that the rotor is hanging loose due to wear on its post. This will cause the movement to be unable to autowind effectively, so unless manually wound, the watch will be running at extremely depleted power and cause timing issues, hence this watch losing time and stopping.
The hands are lined up ready for removal. As always ill place a protective covering over both dial and hands to minimise the chances of any damage being caused.
Dial and hands removed.
I get to work dismantling the movement.
Only the keyless work and motion works remain this side.
In the below picture I have removed the rotor, to the left of the movement you can see where the loose rotor has rubbed in a couple of places on the bridges causing the rhodium plating to be worn away slightly. On this particular movement, its not too bad, but if you continue to wear a watch with a loose rotor, this will only get worse and worse. The good news is it is cosmetic only and will have no effect on the running of the watch. It also tends to look a lot better after a cycle through the cleaning machine.
Ive taken a close up of the barrel bridge below, you can see the fine black dust caused by wear from the post, this ends up everywhere inside the movement! The only way to resolve this is by a full service.
More black dust. The Jewel for the centre seconds wheel sits directly below where the rotor post sits in the auto device, thus a large proportion of the black dust finds its home in this jewel. The dust mixes with the oil in the jewel to form a black paste, this can then in turn increase wear to the pivot of the centre seconds wheel. Ill check this more closely when I begin removing the gear train.
The automatic device where the rotor post would sit, again black dust is visible.
I continue on stripping down the movement, carefully checking each part I remove for any signs of wear or damage.
Train bridge removed, and another shot of the centre seconds jewel.
Luckily the pivot on the centre seconds wheel is perfectly fine. As before, if the watch continues to be worn despite the above issues, eventually the pivot will wear and the wheel will need to be replaced.
I remove the mainspring from the barrel prior to cleaning.
I continue on with the strip down.
Completely disassembled and ready for cleaning.
All the parts are carefully loaded into the cleaning baskets, prior to its cycle through the cleaning machine. At this point each part will be thoroughly cleaned, ensuring all the black dust from the worn rotor post is completely removed from the movement.
All clean, I begin reassembling and oiling the keyless works.
Braking grease is applied to the barrel and the mainspring is fitted.
Train, barrel and train bridge refitted. Notice the wear to the train bridge to the left of the movement looks a lot better after cleaning.
Movement back up and running, with a nice cleanly oiled centre seconds jewel.
No more black dust!
Dial side almost complete.
Dial and hands refitted.
Final checks on the timing machine.
Followed by water resistance checks.
I meant to get a picture of the old rotor post against the new one but I had to wait for the part to come in, and in the meantime I totally forgot. Ill be sure to show that next time.
As always the watch then goes through its mechanical testing, one of which is a test on the auto winding function. Its placed on an auto winder and I am able to tell its now functioning correctly from the speed at which it achieves full wind.
Thanks for reading.
The Watch Professional
The Watch Professional 
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