I'm in the process of changing the battery in my wife's Constellation. What size screwdriver do I need to remove the gold metal battery holder tab? (see pic) I have a set of screwdrivers, smallest is 1mm and that is too big. Appreciate any advice. Happy New Year.
You will probably want to grab a set of cheap watchmaker/jeweler's screwdrivers off of Amazon. They'll probably do the trick, assuming you aren't planning on using them for a lot of tasks.
Now that I was able to remove the screw and change the battery, the screw is no more. It decided to "fly away". The gold bar/battery holder was under more pressure than expected and the screw went somewhere off my work area. It can not be found (add embarrassed emoji here). Anyone know where / if I can purchase a replacement (or a few just in case) ?
You need part 54400 for an ETA 976.001 movement so you should be able to get this from a material house such as Cousins or Offrei.
You should be able to get by just loosening that screw maybe half a turn. The larger part of the forked end of the cell bridle fits under the head of that screw. The smaller tine of the fork sits beside the head of the screw. All you really have to do is to hold the cell bridle down with a piece of bench tissue, lift the smaller tine a bit, then swing the bridle aside to extract the cell. Welcome to the world of noobs who have found out that watch repairs should be left to those who know how to do them.