My watch repairman needs a mainspring for my Swiss Jolus chronograph. I think Jolus is a sort of generic brand name back when everybody was doing Swiss chronographs. The problem is, he doesn't know what type mainspring could be substituted for a Jolus, which he cannot find. Can anyone out there PLEASE help us? He currently has the watch, so I can't give you a model or serial number,etc. but if necessary, I will get that info.--all I remember is it's an 18k Jolus chronograph, seventeen jewels, I believe. Thanks!