The detent screw which you have pointed out holds the detent in place which holds the stem and crown. To remove the stem, slowly unscrew the detent screw while pulling on the crown. You don't want to unscrew it all the way if possible or the screw may become unaligned with the detent and you will need to remove the dial to put it back.
Those have amazing movements in them. They are micro rotor movements made by Bruen. Later used in the caliber 12 chronograph as the base movement.
It probably was sold on a strap originally. The owner then bought the bracelet later but opted for the plated one because it is much less expensive.
Ya I'm not sure what factory they had make the watch. There is no manufacturer markings on the case but it's definitely all Swiss made. There was definitely no shortage of suppliers back then.
This is a cool watch. Rolex had a similar prototype in the early 80s but they ended up scrapping the project. Should be more LCDs with this display.
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