More of a guide than a question. bought a 10K miles 83, headlight didn't work. I had the headlight shell all apart anyways and checked a bunch of stuff then it worked. fast forward a year, on the road to show the bike to a prospective buyer and of course headlight stopped working. Well I traced back, fuse good, 12 volt through it. I am parts rich, so I tried swapping, reserve lighting unit, no joy, starter/headlight relay, no joy. Manual is a bit unclear on this, but the feed for the headlight relay coil is a separate lead off the alternator. (yellow wire) with a connector found above the air cleaner. Anyway took the LH cover off and the outer brush was worn down pretty far, put in a new one (I said I was parts rich) while I was there, I lightly sanded the rings with fine paper and that was it headlight is on. So on a late model bike the headlight not lighting may mean you have a worn alternator brush. Not sure how far back they were wired this way.