As you might have noticed by looking at my Longines collection, I really like the Longines calibre 12.68 series. This one is in need of a service and upper barrel arbor hole repair.
Dial and hands removed and you can see the setting/winding mechanism.
The yoke spring and yoke is all machined out of one part.
The lines and curves of the 12.68 are reminders from it being designed in the 1930’s. It was upgraded with better balance springs and shock protection during it’s production span. It was a great performer right up until it ceased production in the late 1950’s where later models had straight and modern lines.
It’s important to keep track of where the different length screw go.
The weakness of the 12.68 is usually the upper barrel arbor hole.
I make and fit a new barrel bush.
After some machining I see that it fits.
Old mainspring in barrel.
Clean movement ready to be put back together.
Clean mainspring oiled and fitted back into the barrel.
I see the balance moves freely with the cap jewels fitted.