The chronograph brake (blocking lever) is fitted.  This is a white plastic piece for the 1861 but in the previous versions of this calibre, it is a two piece metal part.  It will hold the chronograph when stopped and not reset.

UK watchmaker showing service of Omega Speedmaster - chronograph brake fitted

The coupling yoke will transfer the drive from the base movement to the central chronograph runner.  It consists of these parts.

UK watchmaker showing service of Omega Speedmaster - coupling yoke review

Jewels and bushes reviewed and they are fine.

UK watchmaker showing service of Omega Speedmaster - coupling yoke review

As is the wheel and its pivots.

UK watchmaker showing service of Omega Speedmaster - coupling yoke review

These are assembled and oiled – this one picture is from another watch as I forgot to take one here.

UK watchmaker showing service of Omega Speedmaster - coupling yoke assembly

And fitted to the movement.  It pivots about the upper “screw” which is actually an eccentric to adjust the depthing (mesh depth) of this gear and the driving wheel which is installed after this.

UK watchmaker showing service of Omega Speedmaster - coupling yoke fitted

The coupling yoke wheel is powered from the extended fourth wheel pivot by this driving wheel which is pressed on to that pivot.

UK watchmaker showing service of Omega Speedmaster - driving wheel review

The teeth on this are fine as well.

UK watchmaker showing service of Omega Speedmaster - driving wheel review

And fitted to the movement by pressing on to the fourth wheel extended pivot.  It can be seen that the driving wheel and coupling yoke wheel are meshed so when the movement is running both of these wheels will turn continuously.

UK watchmaker showing service of Omega Speedmaster - driving wheel fitted

The spring for the coupling yoke is then mounted.

UK watchmaker showing service of Omega Speedmaster - coupling yoke spring fitted

This side is almost complete with just the chronograph hammers and hour recorder yoke to fit.