I don't know exactly how to change the spring, but when you need to wind up the recoil you can check this video clip http://www.youtube.com/watch?v=Gxx4oFcr30s
Dunno if the Sea King has the same type of recoil assembly.
This might be helping aswell, even tho it's not the same type of recoil assembly
http://www.youtube.com/watch?v=qTcL3_3leTk&feature=related
If just the tip of the spring broke off, you may be able to re-form it or grind notches in the tip to make it re-usable. Replacing a recoil spring can be an aggravating little job, but just clean all the old dirty oil and grease off it first, take your time, and you can do it! Good Luck!