Not knowing what wires you're using,, or where they're coming from, I've heard folks talk about "annealing" the section that comes out of the plug before working them.
Sometimes a piece of stainless may get work hardened. Maybe the vendor has supply issues and tried something different? One never knows.
But heating it up with a propane torch and quickly quenching in cold water can soften it considerably depending on what you may have to begin with.
Worth a try?