After assiduously removing, inspecting, cleaning and/or replacing, dielectric greasing and switching around ground star tabs for *all* connectors on the headlight switch and fuses 3,4,5 & 6 I now have... 

All lights working again as before EXCEPT passenger lowbeam. I used both voltmeter and a new bulb to test.

When I was first trying to repair the passenger lowbeam, I created a ground to the body on the box-section safety beam behind the front clip sheet metal. It fixed the passenger front flasher and highbeam, but had no effect on the passenger lowbeam, and still doesn't. 

Do I just run a new yellow/black wire parallel to the conduit to... fuse 4, or is there a more elegant solution?