A look at some defective parts

Was contacted by a member who had their Cal. 8400 G watch go in for service just 2 years after it was purchased new. The watch had started losing time, and then it would randomly stop even though it was being worn and was fully wound. It was repaired under warranty, and when the watch came back some parts that were replaced were included, but no details other than that. I was asked if I wanted to have a look at the parts, and they arrived yesterday:



One part is the Frist Wheel, and the other two are the upper and lower balance jewel sets. Putting the wheel under the microscope, it has some wear:



Little surprising after just 2 years. But the item that was more interesting to me were the Nivachoc balance jewels:



The oil in both jewels is discoloured - here is a closer shot of the lower jewel:



The oil under the cap jewels is a brown rusty colour, and this is a sign that these jewels need to be replaced according to Omega. Omega doesn't specify what the exact defect is with these, but they do indicate that the only course of action is to replace them. They also warn that this situation can cause excess pivot wear on the balance staff, but that if the staff isn't worn it can be left as is. I assume since they didn't send back the old balance, that they didn't replace it on this particular watch.

I also note that the guides state that instead of using Moebius 9010 under the cap jewels (the standard oil for pretty much all watches) that when replaced that Moebius 9101 (also known as HP 500) should be used instead.

Interesting to see that despite all the R&D these companies do, that the real test is people wearing the watches day in and day out. Do you all feel like beta testers? 😀

Cheers, Al

Al, do you mind explaining what we're looking at with the jewels? What is the dark red halo inside of the jewel and why is it offset on the jewel on the right in the above photo. It looks like the pivot point is centered on both and the halo is asymmetrical. Is this a depression to hold the oil?

Fascinating! (and a little un-nerving when I think of the two Cal. 8500 G watches I own). So now I'm a bonafide Beta Tester 😀

Balance jewels can be a little tough to figure out unless you have seen them up close. There are 2 jewels here - one in=s the "hole" jewel; that has the hole in it, and the other is the cap jewel. There is a hollowed out portion on the underside of the hole jewel - that acts I suppose as a sort of guide when getting the pivot of the balance staff into the hole jewel. There's no oil on this underside of the hole jewel.

The top portion of the hole jewel is rounded, and the underside of the cap jewel is flat. The drop of oil sits in the gap between the flat part of the cap jewel and the round part of the hole jewel. The drop of oil should be centered, but it's not completely unusual for it not to be perfect. Possible that some dirt or contaminant of some kind has pulled the one drop off center a bit.

So Moebius 9010 is clear and mostly colourless - in significant volumes is has a slight blue tint, but when in a small drop appears colorless. Omega has not stated what the brown is here, however based on the fact that they inspect for wear on the balance pivots, my guess is that this is products of that wear contaminating the oil.


This problem is apparently affecting all of the highly anti-magnetic calibers currently. Not sure what the root cause is, or how widespread the problem is though.

That is the revision level of the movement. Each time Omega makes a change to the design, they assign a revision to the movement designation. They usually follow in alphabetical order, but not in this case...

The 8400 is a fairly new movement, so only versions A and G exist so far. The G was the addition of the anti-magnetic items.

Just a leftover from the manufacturing process. The shoulder of the wheel would ride on the smooth face of the jewel, so these would not be close to the actual hole of the jewel that the pivot goes through. Such things are fairly common and won't cause any wear to the jewels.

I've mentioned this issue in threads several times before - it's not new. But I wanted to share real life photos of the jewels since Stewart was kind enough to send them to me. The first news of this specific problem was posted on the Extranet about 11 months ago, but clearly my source for the post was observing these parts directly in my own shop...

So just to clarify, I've never said this would affect all watches - only Swatch knows the root cause and full extent of this problem, and they are surely not going to tell me (or anyone else) what the return rate is for this or any of the other problems that have affected these newer movements. I have no doubt that if your watch has these problems it will be taken care of, just like they did with the previous problems from the DLC coated barrels, and the hands that would go out of sync. Like those problems, they are addressed as they appear and this is no different. This is something that affects the performance of an expensive wrist watch, not run away acceleration of your car - no one is going to die because of this mate, so relax.

This isn't any cause for panic or to avoid a specific movement - it's part of the growing pains that movements go through over their life span. If you compare a Rolex 3135 made back in 1980's when they were first introduced (to replace the 3035 that had even more problems and was discontinued fairly quickly in Rolex terms) to one made very recently, they won't be exactly the same because specific problems that appeared from longer term use were resolved with design changes. All companies go through this kind of thing to one degree or another, and Omega has been here before fairly recently with the 2500 movements - the problems with those appear to be far more widespread than this one is from what I've seen so far, and no-one issued a recall back then, and I'm pretty sure they won't now.

Cheers, Al