Ancienne Le Brassus
1583
Its a normal problem on many watches, of all brands actually
Hi,
Essentially, it's an issue of a pin slipping off the little notch that i point out.
this is more of a 'watchtech forum' discussion. But the way the stems are held inside the movement (and hence, snug to the case) is by a pin that sits inside this
little notch on the stem.
If the movement moves vertically half a milimeter inside the watch case this can cause the stem to be missaligned inside the movement and become loose.
How this is solved is quite simple, but sometimes for the solution to be permament, the watch needs to be serviced properly with the holder rings of the movement changed so that there is absolutely no play inside.
of course it's a major pin in the rear for something so costly, but remember we're dealing with small mechanical things with extremely small tolerances!!
Does this help? Let us know!
S