Chronographs - Vertical And Horizontal Coupling

It's a bit puzzling really, because if we go back and look at one of the photos in my original post:



There are three wheel involved in driving and starting the chronograph. The drive wheel lower left is mounted to an extended post of the fourth wheel. This drives the coupling wheel, which swings in to contact the chronograph wheel.

Looking at the 3861 parts, the drive wheel is the same one used for all these movements, starting with the Cal. 321, so it hasn't changed. The coupling wheel is also the same one used in the Cal. 861/1861, so it hasn't changed. This tells me that the teeth of the chronograph wheel should be the same, so if that's the case, I have no idea why the 3861 appears to be suffering from this specific issue so much.

It's possible that there is something wrong with the way a bunch of these were adjusted for the depth of engagement of the various wheels that might be leading to this. The guidance for adjusting these is no different that for the previous models, so again it's strange that this would be so prominent on the 3861's.