No Spark help

PS. I assumed its just for the photo but the coil's secondary wire looks loose.

If you find there's voltage drop before the ballast resistor you can quickly check for where the resistance may be.
Check the voltage at the alternator output stud. Since there's no current in that line, it should be at battery voltage.

Turn the key off and turn the parking lights on. Check again for voltage drop at the alternator. If there is check at the bulkheads.
if not sure, turn the headlights on.
This will indicate if the resistance is before or after the ignition switch. If there's noticble drop with the lights on, key off, then the problem(s) is before the ignition switch.

To measure voltage drop you must measure the voltage at the source when the current is flowing (at the battery when things are turned on). Then at different points downstream. You can measure the drop directly or you can measure from ground if you are confident the grounds are good.