My SOP with REPs that are suppose to be water resistant:
upon receipt, do the following:
- Check the crystal to make sure they are properly installed/mounted (I had a GMT-IIc that had an improperly mounted xtal)
- Open up the Case Back and make sure it has a rubber o-ring then grease it.....if not put a new one that had been greased
- Unscrew the crown and release it, check to make sure it has an o-ring, the tube have an o-ring inside and out (triplock)........remember to grease!
- when done.....put back the crown and the CB and make sure its well tightened.
- have it pressure tested so that when you go diving you drown 1st before your watch!
Good luck!