New Calibre 321 chronograph stutter

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Harvey321

·Oct 16, 2025

Hello good people of Omegaforums

I recently picked up a new Omega Calibre 321. Amazing watch.

However, I’ve noticed some unusual behavior and wanted to ask if anyone else has seen this.

When the watch is fully wound, starting the chronograph causes the chronograph seconds hand to stutter (video attached). This lasts for about 3 minutes, after which the hand runs smoothly.

Once the watch is no longer at full wind, the chronograph seconds hand always runs normally. But if I fully wind it again, the stutter returns.

Is this normal behavior or a quirk of the 321 movement, or could something be wrong that might potentially damage the movement?

@Archer I'm a huge fan of your expertise, if you happen to see this, I’d really appreciate your thoughts.

 

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Foo2rama

·Oct 16, 2025·Nowhere near as grumpy as he used to be...

paging the expert @Archer

That is a weird one for a few reasons... I cannot imagine the torque state from the main spring into the gear train changes that much in 3 minutes. Which would lead you to believe that the wind state wouldn't matter much.

But I may be 100% off

 

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Harvey321

·Oct 16, 2025

I can follow your reasoning and have just tested it a few times more.
The issue will only happen at exactly max wind, i.e. when the crown simply cannot move any further.

Maybe I'm over-testing and overly worried ? Given the condition above, the issue would not occur 99% of the time.

Still very curious about what happened in the movement to cause this.

 

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Foo2rama

·Oct 17, 2025·Nowhere near as grumpy as he used to be...

Harvey321

I can follow your reasoning and have just tested it a few times more.
The issue will only happen at exactly max wind, i.e. when the crown simply cannot move any further.

Maybe I'm over-testing and overly worried ? Given the condition above, the issue would not occur 99% of the time.

Still very curious about what happened in the movement to cause this.

come back in 12 hours or so I'm going to bet some people will know the answer. I'm guessing though it will most likely need to go to Omega for service.

 

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Archer

·Oct 17, 2025·Omega Qualified Watchmaker

The state of wind shouldn't have any affect on this, so that aspect of it is strange.

If you hold the watch vertically, so that the 6 o'clock position is pointing to the floor, and the 12 to the ceiling, does the hand still stutter when it is coming from the 6 o'clock position back up to the 12? So when it is fighting against gravity...

Generally speaking, this is an issue from the tension put on the chronograph runner by the friction spring. It needs a small adjustment and that is a quick and easy process. If it's under warranty, it should go back to Omega for this. It won't damage anything by the way...

 

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Harvey321

·Oct 17, 2025

Hi Archer,

I can reliably recreate the issue by winding to the max and start the chronograph, checked what you suggested and the stutter happened for the full revolution (both 12-6 and 6-12).

It make sense to me that it shouldn't be due to the state of the mainspring. How about the position of the crown and the related gears when the crown is turned all the way, i.e. reaching the stopping point? Could that interfere with the mechanism of the chronograph in someway ?

 

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Archer

·Oct 17, 2025·Omega Qualified Watchmaker

When this is happening, does the watch tick differently when you listen to it? Does it sound more erratic than it does when this is not happening?

 

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ErichKeane

·Oct 17, 2025

Could this be the clutch engagement? While messing with my ST19, I noticed a behavior like this if I didn't set the teeth 'deep' enough either from the transfer wheel to the clutch wheel, or clutch wheel to the running wheel.

I could see the 'force' being applied could exacerbate this situation if it was 'close' to adjustment. Either way, that too would be a pretty trivial/small adjustment, even easier than the tension spring.

 

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Harvey321

·Oct 17, 2025

To my ear, there's no change in the frequency of the tick.

I've message the boutique and will probably send it in. Now it's just pure curiosity.

Looking at the movement, I feel that the chronograph wheel is not moving smoothly as well.

 

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ErichKeane

·Oct 17, 2025

What is that logo on the case back over the wheel-over-4th-wheel? I've not seen that on one of these before.

Based on that, it looks like the clutch (the wheel to the left engaging that wheel-over-4th with the logo on it) and the center wheel aren't engaging properly.

There isn't enough detail in the video to tell, I'd have to run it under the microscope, but that can have a few causes. Either a misadjustment (which is a pretty trivial turn of an eccentric screw), OR damage to that or the center runner wheel. Clutch is 1 screw to remove, so not that big of a deal. If the center wheel is damaged of course, the hands come off, which is a bigger ball of wax 😀 Either way, the Omega 321 specialists could fix any of those things easily.

 

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Archer

·Oct 17, 2025·Omega Qualified Watchmaker

Harvey321

To my ear, there's no change in the frequency of the tick.

That was a long shot - it would be very unusual for it to be rebanking with the chronograph running, so if it sounds normal that was expected, but I just wanted to check as that is the only state of wind related thing that could be causing this.

Harvey321

Looking at the movement, I feel that the chronograph wheel is not moving smoothly as well.

Of course - that is what the hand is attached to.

ErichKeane

Could this be the clutch engagement?

More likely to be the friction spring as I've noted.

The stuttering happens because the chronograph wheel's teeth and the coupling wheel's teeth are not staying engaged. The chronograph wheel is being "thrown" forward too far, and then it stops until the teeth of the coupling wheel catch up and then continue to drive it. This is an older video I took, but it illustrates the extreme - with and completely without the friction spring installed.

The coupling wheel is on the right and is driving the chronograph wheel on the left. When the spring is doing it's job, both wheels stay engaged and turn smoothly. When the friction spring is removed, the chronograph wheel gets pushed too far, so teeth are not engaging at times, so it stops moving until the teeth of the coupling wheel catch up. This is the jerky motion of the hand...

 

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Harvey321

·Oct 17, 2025

Oh please dont mind the logo 😀 I had a protective film applied and it's the logo of the service provider.

 

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Harvey321

·Oct 17, 2025

Wow that video really illustrate the differences.

Let say it's due to friction spring, would it cause a permanent stutter and not just for a few minutes at fullwind ? Somehow after running the chronograph for a bit it will help with the tensions ?

 

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Archer

·Oct 17, 2025·Omega Qualified Watchmaker

Harvey321

Wow that video really illustrate the differences.

Let say it's due to friction spring, would it cause a permanent stutter and not just for a few minutes at fullwind ? Somehow after running the chronograph for a bit it will help with the tensions ?

I cannot explain why it only does it at full wind - that is very odd.

 

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ErichKeane

·Oct 17, 2025

For clarification, this picture (taken from here: https://www.watchrepairtalk.com/topic/19319-chronograph-runner-skips-omega-865/) shows the part a little better:

The 'power' from the watch comes from that 'wheel-over-fourth' in the lower right of that image. The clutch wheel to the left of it stays engaged with it and spins all the time. When the chronograph is running, that clutch wheel pivots (with the arm below it) to come in contact to the center wheel of the chronograph (which then drives the minute totalizer, the hour works... differently).

The friction spring he's discussing is the one pointed to there. If it is like the ones I've worked on, it looks like:

The idea is for it to push the chronograph wheel 'up' (in this photo, to the back of the watch!).

So if that spring isn't pushing 'up' good enough for some reason (or the little C shape is off center enough to be causing friction incorrectly?), the wheel could drop below the engagement point (or to a point of lower-enough engagement that the force allows it to skip). At higher wind the wheels 'snap' back and forth faster with the pallet fork, which might be enough force/low-enough-time to skip more readily.

Though, I would expect some sort of positional difference if it was the spring. Here's a question: if you go dial down, does the stutter get worse?

 

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ErichKeane

·Oct 17, 2025

^^ To be clear: I've only taken apart 2 chronograph movements, and am a crappy amateur watch-parts-replacer, so the above is pretty ill-informed supposition based on my experience with other hobbies/etc.

Archer is an actual watchmaker, and seems to be one of the best informed ones I've encountered.

So obviously, take what I say with a few boxes of salt.

 

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Harvey321

·Oct 17, 2025

ErichKeane

^^ To be clear: I've only taken apart 2 chronograph movements, and am a crappy amateur watch-parts-replacer, so the above is pretty ill-informed supposition based on my experience with other hobbies/etc.

Man, you're amazing. Thanks for your insight and especially taking the time to explain the friction spring. I was looking for more details, returned to the forum and voila there was your post. I truly appreciate your patience and the level of detail you shared.

Archer

More likely to be the friction spring as I've noted.

Thanks, Archer, for your expert input and guidance. I think I’ve mentioned before that I’m a fan of your sharing but it bears repeating 😀

I'll check further with the boutique and post an update if the issue is resolved.

 

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Harvey321

·Oct 19, 2025

A bit more update if anyone find it interesting.

Previously, when I wind the watch to the stopping point (i.e. the point where the crown simply cannot further) and release the crown, the crown will just stay there. Starting the chronograph -> stutter as reported.

Recently, when I wind the watch to the same stopping point and release the crown, the crown will roll back slightly. Starting the chronograph now no longer produce the stutter.

As a extreme test, while the chronograph is running normally, I turn the crown to the stopping point and hold it there (don't allow it to rollback), stutter comes back.

I'm probably messing around with the watch too much.

 

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Evitzee

·Oct 19, 2025

Harvey321

I'm probably messing around with the watch too much.

+100. Don't make a science project out of it, just wear it and enjoy it. I don't think there is anything wrong with your watch, certainly not to the point that it would have to be sent back to Bienne for a diagnosis.

On a manual watch I always roll the crown back a bit once it hits a full stop.

Edited: Oct 19, 2025

 

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Indices

·Oct 19, 2025

This is interesting, I remember mine having the same stuttering issue a week or so after I received it; it has not happened since.

I hope your stutter resolves itself also, it would be a shame to have to send it back to Biel.