The FACT:
Yesterday, after a tennis section, dressing my GEN GMT II, it flipped out from my hand to the floor;
I get it in my hands and discovered the CRACK, the crystal was gone.
When I come home I find on my workbench a gen 295c-2 crystal ready for a future project,
so I opened my 16710.
I replaced the crystal, I get a fast ( homemade ) waterproof testing.
Then I get all on the ultrasonic washer too.
I'll get again the waterproof testing from a profy watchmaker this week during too.
et voilà!
Guys,
take in count that only one year ago,
I was not able to remove one link on my bracelet too.
Now I'm able to replace a Crystal too!
Thank you RWG for all the knowledge I get from the forum!
And............. thank you for the tips Domenico get to me every time too.