MAking a spring has worked satisfactorily for me. It would be helpful 
for you to know the wire gauge and length of the spring. Perhaps someone 
can post a photo and provide measurements for that model brace

Stanley 741, SW vintage


Don

Our comforting conviction that the world makes sense rests on a secure
foundation: our almost unlimited ability to ignore our ignorance.
Daniel Kahneman, Thinking Fast and Slow

On 2015-06-30 12:30 AM, Adam R. Maxwell wrote:
>> >On Jun 29, 2015, at 20:56 , Mark Pfeifer  wrote:
>> >
>> >It looks to me like the jaws have recesses for springs. Maybe the previous
owner soaked it in acid, because there are no springs at all.
>> >
>> >Anyone know a source?
> You might get lucky and find a ballpoint pen spring that fits, but I've made
coil springs for 3-jaw chucks by winding guitar string around an appropriately
(under)sized drill bit, held in a vise. It's worth trying!
>
> Adam