Couple of questions concerning Longines 990.1 caliber

[Lieuwe]

Hello everyone. I'm new here at this forum, my name is Lieuwe and i'm from the Netherlands. I'm learning to be a watchmaker, couple of years in it. At home I work a lot on watches ranging from cheap vintage watches to some nice Longines/Omega etc watches. I hope to learn a lot here and also share some of my knowledge

At this moment I'm working on a exceptionally nice movement; Longines L990.1. Considered by many as one of the best movements Longines made. I already serviced the movement and it is running great; very strong amplitude (300+), and almost no deviation in all positions.

On the great interwebz I read that this movement also has a hacking function. Mine doesn't have this Do all the 990.1 movements have this hacking function? Next to the balance I see a slot which could house a balance stop lever. I think some watchmaker before me forgot to put it back.

Here a picture out of documentation from Longines showing the balance lever stop;

Part number 9433 is the balance lever stop, which isn't in my movement. Is it located in the red circle on the right?

I also have quite a lot play in the balance rotor. Is there some way to adjust this or do I need to replace the bearing/rotor? I can't find a separate bearing, only the complete rotor.

Couple of random pictures of this beautiful movement prior to the service;

 

 

 

 

[Nucejoe]

Yes iconic movement, the thinnest.

Have you checked Dr ranfft site for info's, normally provides info on variations with the family. Juat google longines990.1 ranfft. Brings up links to the piece.

For parts julesborel provides some interchangability too.

Julesborel.com

These parts may could be fixed. I,ll check back with your thread.

Regards