I understand you are looking for the screw (only) to the micrometer spring. If so, then your best bet might be to look for a model 7, 8, 9 or 10 parts movement containing that part. The spring shape with that screw are the same for models 7 and 9 while those on models 8 and 10 are flipped but the screw should fit all.
Thanks, Darrahg. That's right: I'm looking for the central screw in the unit.
But if I can't find a replacement, couldn't I take the screw out of one of my other Rockfords and use it to set the regulator? I'd rather delegate that because I wouldn't trust myself not to screw something up, but couldn't you just transfer the screw and use it to set the regulator?
Lee, I am confused. I see a pic of the upper balance jewel with mismatched screws but your text suggests we are talking about the screw the goes through the micrometer spring that is used to adjust the regulator in small increments. Anyhow, yes any related screw that is used in a similar manner should do the trick as long as the dimensions are the same as the original. That is, diameter, thread type and length of the screw.
I share your confusion because I don't know what the hell I'm talking about. I feel the same way when I raise the hood on my car. Lots of stuff under there. Don't know what it all does. But thanks for suggesting that I could have somebody (not the clueless ME) use the screw from one spring (if that's what it's called) to adjust the regulator in another spring/watch. Thanks for your indulgence.