Im not sure what calls you are packing now, but I would go with something different, like a wingbone, or maybe a tube call. These calls have a unique sound and can often get that old lockjawed bird to fire off.
Tate, wingbone is pretty easy to make. I have made a few. Save your next gobblers wing and I'll get you some plans on how to make one. A goblers wing does make a little bit deeper sound than a hens, but dont come accross too many hens around here.