If alllllllllll is well and you place a test lamp on the coils + input and turn IGN ON it should always be lit and a voltmeter should read around 6 volts if points are good and closed cuz the ballast drops the other 6 volts......or 6 volts across coil itself + to -
Now place test lamp over on the coils - side (other lead to grolund) with it still wired to distributor and turn on ign and slowlyyyyyyyy turn the engine over.
LIGHT SHOULD FLASH ON WHEN POINTS OPEN
LIGHT SHOULD GO OFF WHEN POINTS ARE CLOSED
IF ITS SLOWLY CRANKED LIGHT MUST FLASH ON (points open) AND OFF (points closed)
If the wire to distributor isnt connected a test lamp on coils - output should always lite as 12 volts is present
If you work through my troubleshooting procedure the cause can be determined.... Points must close and open to first conduct coil current to ground then open to stop current flow so coil fires.
If the light never goes out (should when points close) the points are bad or not closing or a wires bad/open......If the light on coils - never comes on,,,,,Points may not be opening or condensor is shorted out or theres a short or the coils LV primary is bad/open