I am sure I had to replace (after ten years or so) one of these for the same reason I had a problem installing the one I ordered. The assembly is built with little insulation piercing metal triangles. Tightening the screws theoretically pierces the wire insulation and puts the metal in contact with the copper. To make this happen you are screwing two small metal screws into a plastic base. I tightened it to the point that I was afraid I would strip the plastic treads I was screwing into. I had no current. Sooo, rather than strip the threads (which was the reason I had to replace the original) I used a knife to cut through the insulation, rethreaded the screws and finally had a working unit. Hope it lasts another ten years. All told we love the candles!!