This may sound silly, but try prising the headlight rocker switch out of the dash, then putting it back in again. IIRC the lights earth through the dash, so disturbing the switch may help.
Sorry, only just picked up on this, as I'm not spending much time on the forum these days. Try James Whiting. He kept my Supersprint running like a sewing machine, and balanced my 45 Webers by ear. Got to be worth a phone call.
Good to see you. Mine is a red K-Series Classic with cycle wings. If you're around on the last Saturday of the month, why not pop along to the Squirrel at Penn Street. Just down the road from you. Good crowd, and wife / partner / dog friendly. Nick