If I knew how to fix this by myself I wouldn't have asked in the first place. Yes, it is a quite new watch, but sending it back is not an option as it would be seized by customs by a near 100% chance. So, as I planned to have the Asian 7750 mvt. serviced/lubricated anyway, I suppose it isn't that big deal to have the crown tube/stem assembly changed by that opportunity, too. And, as an improvement, go for genuine parts just there as this seems to be the only true weak spot on that particular rep.
Thanks for your reply anyway. Now I don't feel that ignored anymore ;-)