Omega Planet Ocean helium escape valve (He) removal

[samgher]

Does anybody knows how to remove the helium escape valve (He) of a Omega Planet Ocean (UPO) 45,5mm?

I bought the watch and opened the case back to check if waterproof. A big surprise inside!!! No gasket in caseback nor crowns.

I search the entire internet to find generic gaskets without success. The case uses a non standard o-ring (40mm OD, cross section 1mm) and no references about the crown o-rings. I bought caseback gasket (original) from Ofrei and they told me that there are no available o-rings for Omega crowns because they sell the complete pieces (crown includes the gasket).

I found an assortment of crown o-rings and i am trying to place them. It is a peace of cake to remove the stem (main crown), but dont know how to remove the crown of the helium escape valve (He).

Any advises will be appreciatted!!!