This may be a repeat of what you did already, or I said or didn't say, not going to search that sooooooo.......I will spell it out carefully so I don't screw up.
Here is the next step. If there is a wire attached on the correct terminal of the headlight switch and you know where the other end is, test that end for hot. If it goes hot, attach that other end to the center dimmer terminal and test.
If it does not go hot, or you don't know where the other end is.......take it off the headlight switch, wrap it up and install a new wire from headlight sw to dimmer. Ring tongue to ring tongue. Done.
Too much time spent talking about that center dimmer wire and it's history. What it is, What it was, what it was thought to be and if it's called original or not.
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. - William Penn
