Universal Geneve Space Compax HELP HELP!!!!

I am working on a UG Cal 85 space compax. The crown and tube are intact. The stem is missing. It has a locking crown but the crown only has a female thread. Does anyone know what the schematic is for the Cal 85? It is a Valjoux 72, but it must have some kind of spring loaded stem. Any help is appreciated.

I am also looking for some parts. 20mm UG bracelet ends for Gay Freres original band.

Please advise
John

Yes, this system is spring-loaded with fine internal threads. It is a weak point on these models (along with rubber pushers) and Polerouter Subs Gen 2 and 3. I own several of each of these models and have had to repair one. It is not for amateurs or the faint of heart.