What caused the balance staff to bind in the top jewel?
I am practicing cleaning, oiling and regulating with a cheap ST36. Everything was going well until the top jewel started binding the staff pivot when I tightened down the cock. As in zero end shake!
I did not switch the lower and upper jewels. They are kept in seperate containers and clearly marked. I double checked the cap jewel to make sure it was not upside down. After four attempts at reinstalling the top jewel I gave up and installed a jewel from another moevement. Instantly everything worked perfectly. Out of the box the movement seemed fine. Amplitude was good and beat error was easily zeroed DU and DD.
Attached is a picture of the cap jewel. The black marks are scratches and actual holes in the jewel made by the staff pivot! Amazingly, the pivot does not appear to be bent. Anyone have thoughts on what happened to cause this?
