Tenn, you did not measure it right. The idea is to detect where in the neg path that resistance is, that causes the Vdrop you have measured in the 4th step of your V-4 measurement, you have reported us. Have another look at my explanation in reply#3. BTW, the coils have nothing to do with it. Your lights are dim, so there's either a resistance in the pos path to or in the neg path from that light, a resistance that 'eats' volts so to speak. The 4th step was to check the neg path. It is there you found a considerable Vdrop, provided you have informed us correctly. Now you have to detect where in the neg path that resistance is, that causes that Vdrop. First suspect is where that green wire contacts the frame because it happens to be part of the neg path for the volts to travel from both the headlamp and blinkers via the frame to the Batt minus, so there's a good chance the problem is right there. Have a look at the pic Ozzybud has posted. That connection does not look particularly good, does it. It looks corroded. Yours is maybe as bad as Ozzybud's. Put IGN key in ON and the headlight or a blinker ON and then one probe on that green wire and the other on the Batt minus. Report what voltage you read. Ideally it should be zero. But I expect you will read a couple of volts which indicates not all volts make it to the Batt minus, because of a resistance where that green wire connects to the frame, probably caused by rust. This resistance 'eats' volts. Reread reply #3 for the principle of the V-4 measurement. It's dead simple.
If you fail to understand it, then just disconnect - key switch now OFF - where that green wire contacts the frame and clean, de-rust the eye connector, the bolt and the spot where the bolt contacts the frame. When needed, use sandpaper, so there will be a perfect ground. Reconnect and see if your lights are now brighter.
