I have a win.model 12 1936 patent nickle steel...a lovely shotgun handed down from grandfather/father..me...I screwed it up by putting on bars of a 3 wheeler going through fire trails bird hunting. I put 1 dent in tube mag. that will not allow shells to move past that point. I have tried everything to push dent back out without luck..I am now intent on replacing entire tube mag. spring/plug....where is the best place to search...I may not ever shoot this shotgun again but I'd like it to be in working order..thanks much if you can help