I am restoring a Tissot calibre 2481 automatic movement. I have fitted a new mainspring and pallets and have a new balance complete to fit but this is for calibre 781-1. the original hairspring is badly damaged and broken off flush with the stud and I cannot see how it was fixed to it. There is a slot in the top of the stud head and a flat, I assume for adjustment.
The Problem is, how do I remove the stud, as there is no screw at the side as in the conventional fixing, it looks to be pressed in, Is the replacement I have interchangable with this. I believe some of these balance springs have no stud, but then how is the spring fixed ? it isn't with a pin as in the conventional way.
Not seen this type of stud before,
Can anyone help or advise ?