ballast resistor burn out

A bad fusible ignition link, or bulkhead connector, will/can pass voltage but may not supply enough electrons. Give yours an inspection.
For testing purposes, you can run the coil plus side jumped straight to any battery voltage.
A 4-pin ECU can also be jumpered straight to battery voltage
A 5-pin will overheat, so not recommended.
The ECU wants to see a minimum 9.5 volts and needs a solid ground.