My friend John Ennis was just here yesterday using my mill to thin a section of spring for sidelock that he is working on. If you dont find one,he can make one for you.
In addition to the above suggestions it actually is possible for a skilled TIG welder to repair a spring. Admittedly finding such might be harder than finding someone to make a new one. Offhand I"d guess it's not an off the shelf type part and is hand made anyway but I'm biased by experience with UK doubles.
Jeremy