Not knowing what tests you have done so far and if the primary is open or back together. I would if it is together do the recommended tests with the engine at normal operating temperature ( hot enough for the primary to reach its normal temp ) and check the stator for an open in the windings. I have seen in other electrical equipment where a fracture/break in the actual copper windings will open up as the windings expand with heat and make contact after the windings cool off.