OK, you amateur watch repairs/ hobbyists, like me. Breitlings are not for the faint of heart. You have an expensive, glorious timepiece you love. As an amateur watchmaker/hobbyist, my advice is be very careful and sure you really want to do this. There's a You Tube video on how to dis-assembly one of these beauties. Having said all that, I wanted to regulate my Navitimer that was running minutes a day fast. This opener let me get in at a tiny fraction of the big-boy case openers cost. My advice, invest in an electronic beat count timer and dial your puppy in. Be careful every step,