Troubleshooting
Go directly from the pos terminal of the battery into the dimmer switch (at the mass of connections under the tank), headlight works in high and low beam. The dimmer switch isn't getting power through the black/white wire.
Black white wire goes back to the fuse box, goes through the headlight fuse, then turns black/red as it heads up to the starter switch.
So the starter switch should normally make the connection to the headlight when running but MAKE the starter connection and BREAK the headlight connection when you push the start button. So if I'm right, there is a bad connection in the starter switch when the button is normal?
Does this sound right? Is this a common problem and what's the best way to clean/fix this switch?