Trying to get a 78k cb750 running again. I had a friend install a new wiring harness (because I have no experience with electrical work). I just installed a new headlight assembly which is metal and not plastic (might make a difference?). I plugged in the headlight and turned the key. It came on but was accompanied by a high pitch buzzing whining noise. The headlight is grounded to the mounting bolts. Is the metal casing making that noise or are the wires messed up?