I have a 1959 Bulova 23 that looks like it has a weird movement. Wanting to know if it's a quirk of this movement or something possibly needing repair. First the sweep movement isn't perfectly smooth. Looks like there is maybe 5 to 6 distinct movements per second. If that's how the Bulova 23 sweep works, that's great. The thing I think is odd and maybe wrong is that the second hand jumps those 5-6 movements one second before the minute hand on every rotation, no matter where the minute hand is. It keeps good time and the second hand makes a clean 60 second revolution each time around. Is this normal for the Bulova 23? This is a 1959 model EAW if that matters.
Not sure I follow. Many vintage movements have a beat of 300 to 360 per minute, so 5 to 6 beats per second is normal. I'm not sure if the 23s have a higher beat count, I don't think so but could be wrong.
I'm trying to understand what you are seeing with regards the "jumps those 5-6 movements one second before the minute hand on every rotation"....can you elaborate?
Two scenarios.
- The seconds gear is warped or missing teeth. As it disengages with the teeth it slips than catches again when it is swings back to the teeth.
- Bad pallet fork or escape wheel.
Either case it requires a service and inspection. I would not try to run the watch as it could damage it. I actually have an Oceanographer that does the same thing that I have not got around to inspecting yet.
Another thing to consider along with that Jim mentioned is that it was common for these Bulova 23's to have a sweep seconds pinion that is driven by a large driving wheel that sits on the extended pivot of the third wheel. This type of setup allowed for movements that used to have a sub-seconds hand to have a center sweep seconds hand without having to completely redesign the movement by essentially just tacking on a couple of new parts to the existing movement. One issue with this setup is that the seconds hand can have some 'backlash' where it appears to stutter. To counter that a spring is used that rests on the top of the sweep seconds pinion to prevent that. If the tension isn't just right it can cause the seconds hand to jump erratically.
It's hard to tell from what you are describing but if the second hand movement looks like the one in this video then it likely is caused by an incorrect amount of tension in the spring that rests on the top of the sweep seconds pinion.