My brothers watch ID

[markr]

My brother sent me his watch.  It needs a new mainspring.  Any help with a make and model would be appreciated.  Bonus points for a part number.

[Poljot]

15 minutes ago, markr said:

My brother sent me his watch.  It needs a new mainspring.  Any help with a make and model would be appreciated.  Bonus points for a part number.

If you just remove the barrel and extract the mainspring it will be easier to help.

You basically need to measure the barrel ID, arbour's OD, and barrel's depth. Then it's easy to calculate the mainspring strength and length. And hope that calculations are accurate . If you are lucky to find the original mainspring inside your watch, then you can take measurements and compare with calculated results. Part number can be obtained from GR catalogue once you have your mainspring Height, Strength, Length numbers.