I need a new mainspring for my current repair. Unfortunately the exact one I want is discontinued. There are alternatives with the same spec, other than the length. The specified length for the the correct part is 320 for a 10mm barrel. I have options either side of 300 for a 9.5mm barrel and 380 for an 11mm barrel. As I understand it, the stronger mainspring would increase amplitude and possibly slow the escapement because of it. And the weaker would do the opposite, and may under-power. I