Funky Second Hand Datejust

[tintrains]

I have a really nice 1601 Datejust.....keeps good time but the second hand movment seems a bit off.

As it passes over the 5 dial marker it gets jumpy, almost like a pause and then it contues, not just over the 5 directly but this will pause breifly and jump a second or two mostly between the 5 and 15.

It may do this in other spots but not as consistent.

Thoughts? Its baffling as it keeps good time.

[Spectre007]

It may be a "stutter" but if it was recently serviced that shouldn't be the case.
Most likely it's because it's an older lower beat movement (<28.800 vph) which makes it look less smooth than a more modern iteration

[estorlie]

The seconds hand is indirectly powered on a 1570 movement, which is most likely what is in your 1601. This means that the post the seconds hand attaches to is not part of the powered gear train but is indirectly geared with one of the wheels of the regular gear train. Because of this, there is no constant tension on the second hand post to keep it still and it will sometimes "jump" or "skip" because of the lash in the gear teeth. To fix this, there is a spring which presses against the second hand post in order to give it tension and make it run smoothly. Most likely that spring has just a tiny bit too little tension and is allowing the second hand to occasionally jump. A simple fix, but also not a problem that will negatively affect how the watch runs.