Mean time screws?

[Stevelp]

Good morning everyone, I hope this message finds you all well and healthy!  I have a question in regards to a ladies Bulova watch that I am currently working on.  The watch came to me with a broken hairspring and I just so happened to have a parts movement in my stock.  The movement is a Bulova 6AH.  After servicing the movement and swapping the the donor hairspring the watch starts up and runs nicely.  After putting the watch on the timing machine it showed otherwise.  The watch ran at +600 seconds per day with the regulator arm central in the balance cock.  After inspecting the donor spring more carefully, there was a larger patch of rust on the spring.  I put the spring in the ultrasonic to try to knock off the rust and visually it looked really good after doing so.  After reassembly the watch now shows +445 seconds per day which is certainly an improvement but not where it needs to be yet.  The beat error is at 4ms so i will take care of that first.  So I'm thinking that maybe the rust that was on the spring has done some lasting damage to it and that is causing the issue.  The person I am doing this for does not have to budget to spend on a new hairspring but I would like to do what I can to get this right for them as it has sentimental value.  So my question is, are there any mean time screws on this balance that I could adjust to slow it down?  I'm used to balance wheels that have the 2 screws in line with the balance arms and I don't see anything like that here.  So can anyone tell me how I can use what's  here to slow it down?  Any input would be much appreciated! 

[Poljot]

Small calibers - pleasure to work with .. NOT.

It's impossible to tell what went wrong simply by looking at the photo you provided.

I would loosen up the balance cock screw while watch is running to see if the hairspring pin would readjust its position. Sometimes we fix the pin in a slightly angled position (see photo attached).

And you do not have to keep the regulator in the middle position, right? Move it to make hairspring longer - this will slow down your watch.

[ddrescueb2048]

I just finished my own thread about something similar which might be helpful. Consensus in my thread was the hairspring and balance wheel are paired to each other and can't simply be changed around like it would appear. I've done a good bit of research on the subject outside of that thread and found numerous other references stating the same thing. I'll leave it to someone more experienced to offer some more direct guidance to you but thought I would mention this as its a current affair of my own as well. Good luck!

 

[Stevelp]

Poljot, thanks for your quick reply!  Yes they sure do present their challenges that's for sure!  Yes, I'm aware the regulator does not need to be centered, I just like to get the timing as close as possible with the regulator in the center before I start to use it.  And as much as its gaining the regulator by itself won't be able to take care of that kind of number.  That's a good idea with the stud screw, I will give that a try! The main reason for the picture I took was to show the arrangement of the screws wondering if any of them could be identified as the mean time screws, as there are no obvious ones at the balance arms which I am used to.  

[Stevelp]

That's a great thread ddrescueb2048, lots of great info in there!  I'm starting to think that is the case with what I'm dealing with.  I did count the number of coils from one to the other and they seemed similar but close doesn't always cut it in the watch world!