Before you return it, try bench testing it. Clamp it in a vise. Remove all spark plug wires. Remove the cap but leave the three wires connected to the base. Hook 12 volts to the cap as usual with a battery. Ground the base to the battery. Now, most important, make a ground for the spark. I like to take a coat hanger, attach one end to the battery negative, or the base, and rig it so the other end is near the coil button on the inside of the cap. That button is what sends the spark from the coil to the rotor and the rotor 'distributes' the spark to each terminal. By having a grounded coat hanger wire right near the button, the spark can jump to it and not bite you. Now, if you spin the shaft by hand, the coil will fire every time it would as normal. The spark should jump to the wire and as you pull the wire away from the button, [with insulated pliers and thick gloves] the coil will increase the voltage needed to reach that wire. I have gotten the spark to jump 12 inches or more. That is how powerful the HEI coil is. This is how you judge the HEI. If you get a healthy solid blue spark that can jump several inches, you are good to go. If it's a weak orangey spark, or no spark, something is wrong. Just be CAREFUL as the HEI can put out up to 20,000 volts. It hurts like a MF'er, ask me how I know.