I read in an old watch repair book that in order for regulator curb pins to work properly that the hairspring must be in contact with them for at least 90% of the time. After a complete overhaul, I have found several times that with pins too far apart the watch runs too slow even at the fastest regulator setting. I try to adjust the pins as close as possible while still allowing the hairspring to slide between them. If everything else is good, this can make a big difference.

Hi Rodger,


This is just one of the many adjustments around there that can have dramatic effect on the running and setting these up correctly so they hold but not grab is not easy (many a watch hairspring damage with these incorrectly set).
One of the most common errors you will see in the watch running great until you get in one or more positions, the hairspring has been resting against one pin and running fine once moved to a position (due to gravity) it starts bouncing between the pins and each time for the split second the hairspring has increased in length by the distance from pins to stud, (hope I explained that well enough) suddenly a huge timing error come into play then disappears again as you turn the watch or take the next step!.....

Remember to keep the pins parallel when adjusting..

Last one I did- used an old small ladies ww mainspring to keep the gap. Just closed it on the spring and pulled out the old mainspring.