Hi Suitbert,
It was a guess born out of hope. The hope that you will give us some more insights of this magnificient watch. When the masthead picture appeared I figured you spend some time with the watch, so when you asked about the hacking Patek the 5959 came to mind.
Anyway, it still is a bit of a surprise to me, as you said the 5959 has a very traditional movement. Is it a normal hack mechanism (put some metal against the balance) or has it perhaps something to do with the new teeth profile. Perhaps a fixed wheel, or only a small arc with profile, that is moved against the wheel that is connected to the 4th wheel (what's its name....). The profile is designed to prevent jumping of the seconds hand, so perhaps it can be used to stop the movement altogether without jump in the train... (I am not sure if this makes sense at all
)
Have fun in Basel, I see the first pics are up! What a wonderful time of year!
Regards,
Joram