Thanks for the vote of confidence, but no LOL. I have seen systems that make weird noises when they should not. I'm with "the others" My best guess is the box. But before you replace it you might try jumpering power direct to the coil with the key on. "It might be" some weird bad connection is causing the thing to go into an oscillation loop here is how that might be, and I say, "might."
"Let's say" there is a bad connection or component in the power feed. Maybe the igntion switch is OK, maybe the bulkhead connector is OK. Maybe there is a bad connection at the ballast, or it's actually broke and sort of just "touching" internally
You turn on the key.........The system surges on and draws some current.......this starting surge of current produces one spark.
The bad connection breaks or becomes "poorer" due to the inrush current. The bad connection /component drops power down to either nothing, or so low the box can't do anything. Current drops out and stops. The bad connection remakes, the box draws current, another inrush of current, another spark, and the thing does this all over again.
It's called an oscillation.
A poorly designed ignition "flasher". LOL