Hi i am new the collecting of Bulova watches, up to about 8 now, i have a 1926 Presedent with a 1927 6AE 21 j movement that will not regulate and keeps running very fast, i have demagnetized it still no luck,the hair sring is not touching. being an amature and still learning i dont want to strip this one, any pointers or is it to the repairers to sort out.
This can be caused by quite a few things. It is possible that the hairspring has been either badly adjusted or replaced incorrectly. If you use a tunnel type de-magnetizer it will only make magnetisation worse. The coils of the hairspring could be either touching momentarily or sticking together. The amplitude could be low which may make it run faster. The regulating pins could be too close together or they could be clamping down on the hairspring as it vibrates.
Other variables might include an insanely strong mainspring (you'd probably notice this, it would make the balance 'knock') or even a really bad beat error.
The only way to know for sure would be to put in on a Witschi and see what the graph looks like, so I would recommend getting the fault diagnosed by a qualified watchmaker.