Had the head of screw strip off the mainspring barrel arbour. Tried to use a bergeon screw extractor and failed. So I set the arbour up in a lathe and graved a small cone center. Then I used circuit board drills and progressively drilled out the center. And after two broken bits, I finally got the insides loose. Then I went on my Stereo Microscope and picked out loose parts using rodico and a small pink screwdriver.
All worked well. Now to find a new screw. The main mission was to replace a broken mainspring.
And here is the broken mainspring.
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