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The superconducting properties of Nb₂Pd_xSe₅ are highly dependent on the Pd stoichiometry. We have synthesized single crystals of Nb₂Pd_xSe₅ with x in the range of 0.68 to 0.96 and have carried out detailed single crystal x-ray structural studies. We observe a pivotal shift in the atomic positions that depend on palladium occupancy at the threshold for superconductivity. We will discuss the crystal growth process, our recent findings of the subtle but profound structural changes, and present the rich spectrum of electronic behavior observed for different Pd occupancy regions. At the threshold Pd stoichiometry for superconductivity, a miscibility gap is apparent, with commensurate change in the electronic transport properties. Electron-hole competition in this two-band system is thought to be responsible for this behavior.