If it was me I would first just massage the spring at the 07:00 o'clock position. You might be lucky in thats all thats need moving.
What I call the terminal curve (Blue) is critical that it has a uniform curve in relation to the curve of the main body of the spring. If not when regulating the spring it will go out of centre.
... and here it is half a day later. Things are settling down quite nicely.
Bear in mind that other than cleaning the random bunch of BFG866 parts, and throwing them all together, I've done nothing else yet. No regulation or adjusting.
Sorry, I can't. I have sworn to an inner circle of initiated to never revel the secret magic place where one can get any watch part. Pretty much like unobtanium, it can be mentioned, but never achieved .