The typical reason for this sort of damage is someone brutally swinging the regulator around in an attempt to regulate the watch but, it can be as simple as catching the spring with the tweezers or a screwdriver. You will be very lucky to just find a suitable hairspring. The reason the balance and hairspring are sold together as "balance complete" is that they are a matched pair so, will vibrate at the correct rate. At least you have a balance with screws so, the mass can be slightly adjusted to match another 320 hairspring but, this is all more work for the watchmaker.
You should get a watchmaker to remove the balance and look properly at the spring as this sort of damage is not unusual. Here's an example that I show on my website - it's a flat hairspring from a 1950s Eterna and, looks a bit of a mess here. The red arrow shows the outer coil pulled out of shape and the green arrow indicates the rest of the spring is right over to one side - looks very bad...
View attachment 824801
Balance removed. The spring is pretty good overall but that problem on the outer coil deforms everything when the balance is mounted. Not everyone will tackle something like this so, you should try one of those people recommended in the other thread.
View attachment 824804
Some work later and the balance/spring is ready to go back onto the cock to make final adjustments. It's not perfect but, it's close enough to be able to work on when re-fitted.
View attachment 824803
Like I say, get it reviewed by someone who might take it on as this will probably be the easiest way forward. Hope this helps.
Best regards, Chris
Click to expand...