Terminal N in the bulkhead connector is where the Dark Blue wire from "run" on the ignition switch feeds power thru to the ballast resistor. This is most likely where the fault lies. When the ignition switch is in the start position, it bypasses the ballast resistor and send 12v to the coil via the brown wire and terminal Q on the bulkhead. This is why it will run in the start position. Clean terminal N, or bypass the bulkhead connector by locating the dark blue wire on both sides of the firewall and tie them together with a separate wire thru a hole in the firewall.