I have an 18 size Ball Hamilton 19 jewel sn 497820 double roller with a broken balance staff. Would that staff be the same as for the Hamilton 944 which my material catalog lists as a part # 126? Also is the mainspring also the same as a 944? For this sn I assume would be the Hamilton part # 232 for the "new style motor barrel".

Hi Rob, the mainspring is a Hamilton #15 and the staff is #126 double roller large collet. regards Joe

Thanks very much Joe. That is what I thought the balance staff should be. For the mainspring, I got some information after I did the original post that indicates the mainspring should be the same as the 19 jewel 944, which would be a #14 if it has the old motor barrel or a #232 for the new motor barrel. I think based on the serial number it should have the new barrel, but I will have to determine that when I do the COA.

Just to set the record straight on which staff and mainspring this watch needed. I did a COA under the guidance and occasional help of my watch maker friend. The staff is a 126 small collet and the mainspring is a #14 for the old style motor barrel. Fortunately he had both in stock which surprised me since he primarily works on high-end wrist watches. We didn't have time to do any adjusting but it showed 1 1/2 minutes fast per day on the timing machine which is what is has been running for the past couple days.

Hi Rob, my appologies on both quotes. I'm glad your watchmaker had both items available. Makes sense the mainspring is the same for a 23j watch since your 19j has the same 3rd eye...blink blink. As for the # 126 staff with the small collet, I never seem to remember or get it right which is why I keep one small collet and one large collet in my stock bin. glad your all set, please post some pics.... thanks and best regards Joe

Joe, you confirmed that the staff is a Hamilton and not something special for Ball which was my main concern. Even though the dimensions of the new staff were very close to the old one, the small roller was not tight enough so we had close the hole slightly with the staking set. Here is a picture of the now running movement.

Here is the face.

very nice, enjoy!!