[Bike...and Dennis]

My '76 CB550K and '80 CB750F both had running light/blinker combination. What I can't remember is if the running light went out to cause the "blink" or if there was a dual filament bulb. The rear was single filament on both.
I'd drag up the fiche and see what bulb is called for.
There's a fair chance some PO just put rear, single element signals on the front of that bike.

 

[Bike...and Dennis]

OK, the front does use a dual element bulb. (23/8W)
The turn signal should have a harness coming out of it with 2 wires which end with bullet connectors. Those wires should have a recepticle in the headlight.