havn't personally used these yet, but i'm told a spring out of a BIC lighter will work as replacement.
i replaced the spring, and little cap along with it, in 2 frames recently. i got these springs from a good friend, so, i can't help you much on finding that exact spring.
it's very easy to take apart, and put back together. you can do it. :wink: i can't think of a good way to explain it. maybe someone better at explaining the procedure will drop in. :-)