I have an A. Schild watch movement with a broken mainspring. Searching around I found that the Marathon No. 745 is the right replacement. The numbers are as follows: 7 x 11 10 1/3 which I assume mean:
Dennison width: 7
Dennison strength: 11
Dennison length: 10 1/3
However what I'm calling the Dennison strength could actually be the Dennison length, not sure.
There are two other numbers on the Marathon 745: 1.6 x 10 which I take to mean:
Metric Width: 1.6 mm
Metric Strength: 10
1) Is my interpretation right?
2) Would a spring with the following be a proper replacement?
Dennison width: 7
Dennison strength: 11
Length in inches: 10.5