It can be a very tough job depending on how rust welded the stub of the spring is to the wall of the hole in the frame where it sits. When an action is clean, the spring will often drop out under force of gravity or minimal finger pull pressure. Soaking with penetrating oil or heavy duty radiator cleaner might loosen the rust or might not, as the fit of the stub to the drilled frame hole is fairly tight when rusted. A large ultrasonic bath of the frame might help, if you have access. A thin bladed wedge shaped screw driver or small chisel can be inserted between the spring and frame and "gently" tapped with a small hammer for several minutes (gotta have patience). Resist the urge to apply heat from a torch, as warped frame could result. Localized heat from the tip of a soldering iron might help. It is a frustrating job but since the spring is broken, you have to get it out. Good luck. (I suppose it could go to a gunsmith, but there's no fun in that for a do-it-yoursefer)
Cheers,
Jack