I purchased a nice looking Hamilton Grade 974. At the time of purchase, all it seemed to need was a new balance staff. I replaced the staff,and checked the timekeeping of the movement. In twenty-four hours of running, the watch gains 1 hour. That is with the regulator set at mid-position. I don't think the regulator would have much effect in slowing this movement down to where it would keep proper time. I have no idea if anything else was changed out of the movement, to affect it's time keeping qualities;hairspring,balance screws,etc. Any help appreciated, to slow this "horse" down.


Frank

Hi Frank, Is the hairspring hung up on one of the curb pins? Is there a drop of oil on one of the hairspring coils? Did the hairspring become magnitized during the repair? Just thinking out loud.

Tom

Frank,
Another easy to check for problem is a missing balance screw. Make sure that all the screws are in pairs exactly across from each other in the balance. If they are all there, the problem is almost certainly in the hairspring, as Tom explained.

Frank,

Just a few more things to think about:

1. Does the hairspring move excessively between the curb pins? This can cause the regulator to be less effective but probably not an hours worth!

2. If applicable, did you turn any meantime screws all the way in?

3. Is the hairspring stud seated fully in the balance cock?

4. If applicable, does the hairspring overcoil make contact with the balance cock?

5. Is the watch in beat?

6. Did you poise the balance after installing the staff? If so, did you remove much weight to get the balance in poise again?

7. Someone may have robbed a pair of screws from the balance before you got the watch.

If everything else checks out okay with your watch, it sounds like a small pair of balance screws need to be added and go from there. If your lucky, you may end up being a few minutes fast per day and then can add a pair of timing washers.

Wow,great info here from guys who know!

One other problem that I've run into is the actual dept of the stud in the balance cock.I have set them too deep into the opening,just to have them run erratically-when I decreased the dept of the stud,they fell in line and ran better.I believe the H/S was tight against the cock,thus introducing rub or (effectively) shortening of the H/S

Great advice guys.

Be sure to let us know what you find out.

I dont believe you can set the hairspring stud too close on a Hamilton though.

Tom, Ed, John, Sam, and Aaron.
I have printed out the list of suggestions offered by you guys, and I will check each and every one of them, as soon as I can get back to work on my bench.This was a problem I was about to post, when other duties called. I will let you all know what I find.

Thanks for the suggestions as to where to look for the problem.

Frank