Missing Omega symbol on 321 movement (Balance bridge)

The regulator works by changing the effective length of the balance spring by restricting that spring between some pins. The longer the effective length, the slower the watch will run, and the short the effective length, the faster it will run, all else being equal.

So to change the rate, you move the position of the regulator pins on the portion of the overcoil that comes out from the stud in this case. The regulator isn't a straight part, so there is an angle between the indicator that shows the fast or slow marks, and the pins. That angle changed significantly when the change was made to the regulator shape, so if you set an older style regulator at the same mark on the balance cock as a new regulator, the spot on the overcoil where the pins are acting on the spring is dramatically different.

When the regulator was changed from the "pointy" to "lozenge" the balance was changed - you can see here that the part numbers have a suffix for the newer parts:



Here are the regulators turned upside down, side by side so you can see the difference in the angle between the pointer and the pins - red lines added to help illustrate this:



These are not parts that can simply be swapped. Trust me I've been there and won't ever go there again, as it required a lot of work to get a mixed set running right without having the pointer of the regulator way off to one side. Along the way fighting balance amplitude issues, so unless the watchmaker in this case was very dedicated, they likely swapped the balance as well.

Things like this are why when people make statements that the "new" 321 will have fully interchangeable parts that can be used to restore vintage watches, my only thought is this...🙄

Take claims made that the new movement will solve all the parts problems with a big grain of salt mate...it ain't necessarily so...and people making such claims usually have no idea what they are talking about.

Cheers, Al

Glad you could follow it - I try to write things so they are easily understood, which is not always easy with watchmaking. None of this is rocket surgery, but sometimes I'm not sure how fundamental I need to be with where I start to explain things. Hopefully if something isn't clear to someone, they will speak up and ask for clarification so I can explain it further...

Cheers, Al