I have a Buffalo Bill Commerative Rifle. I bought it used se...

I have a Buffalo Bill Commerative Rifle. I bought it used several years ago and use it to deer hunt on occasion. I am looking for a spring, the one that goes in the loading tube, mine has gotten weak and will not let the last round out to be able to lever it into the action. It does excellent until that last round, this tells me it has to be the spring. Where would I get one? I presume the carbines is way to short. Sincerely R.G. Davis