Ted,
How are you testing it? With just a six volt battery? That isn't a good way to test them, especially for long runs as it will destroy the inner windings. The only way to properly test a coil is with an ohm meter first to check for internal shorts and a HCCT or a Strobo-Spark Coil Tester. Other methods may get you close, but without one of these tools you are only doing half of the adjustment.