I can't remember if I shared this, but one of the first things that happened to the first Seagull ST3600 I bought, is that the balance wheel simply fell off during reassembly! I assumed I must have been too rough with it, but as it turned out, there was insufficient adhesive on the stud to keep the hairspring in place.
So into a box it went, as I continued to work on its replacement. In the back of my mind, I wanted to come back to it once my skills (and magnification) were up to the task. So I took a stab at it today, with some UV glue, and a working balance for reference.
Here's the balance cock with balance removed (well it fell out). No trace of glue on the stud:
Regulator pin is closed on the end, so the hairspring will need to be slotted in from the side:
Hairspring is threaded through the regulator. I used a working balance to aim the roller jewel in the right direction, with the intention of fine tuning later:
I used UV glue, applied by a red oiler:
My improvised UV curing setup
Initial timings look promising! I got it to 1.1 just by eyeballing it
My only goal was to get it within spec roughly in one position. I'll look at the rest later
I guess the main thing I learned during this time is that using a microscope has completely changed what I can do, in every task related to watch repair it can be applied to. I feel like I have really good control over the smallest parts, as long as I can see it clearly. I was struggling quite a bit using loupes.