3861 movement broken? *Update: Read First Post*

W Woland91

Hi everyone!

My name is Igor, and I have been a long-time fan of Omega in general, and the Speedmaster Moonwatch in particular. In 2026, I became the happy owner of a Moonwatch powered by the 3861 movement, with a sapphire crystal caseback. A couple of days ago, I ran into a problem with it.

It all started with the fact that, ever since I bought the watch, it had been running at approximately +0.5 sec/day, gaining around +16 to +18 seconds per month. At the end of August 2026, however, it suddenly stopped gaining time and started losing about 1 second per day.

At one point, I started the chronograph and, to my surprise, noticed that after running for just 2 seconds, the entire watch stopped - both the chronograph and the small seconds hand. I pressed the upper chronograph pusher as if to stop it, then pressed the lower pusher to reset the chronograph, and the watch started running again.

I immediately tried starting and stopping the chronograph about 10 more times in different ways, and everything worked perfectly. Almost reassured, I decided the following day to run the chronograph for an extended period. After approximately 2 hours, the chronograph stopped, and the entire watch stopped with it.

At that point, Google led me to this forum, and I started reading through this thread. Needless to say, my mood gradually got worse. Eventually, I decided to perform one final test: I fully wound the watch and started the chronograph.

With a full wind and the chronograph running continuously, the watch ran for 6 hours, 28 minutes and 58 seconds and then stopped - specifically at the 58-second mark. I can also add that during those 6.5 hours, the watch had lost another 5 seconds in elapsed time - which seemed unbelievable to me.

I then reset the watch to the exact time, fully wound it again, and started observing it. Over the following 24 hours, with the chronograph completely switched off, it lost 11 seconds.

Today, I took the watch to an official Swatch Group service center. I bought the watch in 2026, but I am its second owner. The first owner purchased it on February 20, 2023, which is when the warranty period started. As far as I understand, the watch should still be under warranty, since five years have not yet passed.

I do not know the actual production date of the watch. The serial number starts with 831xxxxxx. The cardboard box in which the original presentation box is stored is marked “10/21”, but I have no idea how, or if, that correlates with the actual production date of the watch.

I also don't know how long the chronograph issue may have been present. I don't use the chronograph every day, and previously I had never run it for more than about 1.5 hours at a time, and everything seemed fine then.

What I do know for certain is that until the end of August, the watch was consistently gaining time, and then it suddenly started losing time. That was a very clear and noticeable change.

Moreover, thanks to the transparent caseback, I can see the balance wheel, and I have the impression that it has slowed down. I am not a watchmaker, so I cannot say this with any certainty, but visually, that is how it appears to me.

For now, I am waiting for the results of the diagnosis. They told me it should take up to 20 working days. After that, they will let me know what the cause is and what options are available.

4011021

Похоже на классическую проблему с втулкой, которая всё ещё встречалась у часов, купленных в начале 2023 года, а возможно, и за несколько месяцев до этого. Они должны устранить её по гарантии, и ваши часы будут в порядке.