Crown gasket for 6309-7040 - Im sinking

So i changed to my 6309-7040 today and went for a shower and after i was blown away :-\ the watch had taken on water and the fine mist on the inside of the crystal was very small but still it was there. to my surprice the gasket in the crown was gone :-[ the watch had been to my local watch shop for a service about 3 months ago so im not going back there again.... Im now fed up with the local watch service here so this one im doing myself..

But where can a get a gasket for the crown ? Do any of you guys have one that i can buy ? I would hate to order one of them Philli gaskets that don't fit proper or hold up.

I made the test just now with the crown from my Quarts 6309 and this worked fine with no water any where in the case

Hope to get a little help here