I drive an '81 300D.

I was driving home from work one night recently and I quickly noticed
that I was riding cyclops.  The right low beam was out.  I flicked the
turn signal stalk back, and both high beams came on.

I took this opportunity to replace both headlight units with new
Sylvania H6024XV sealed beams.

When I got the replacement lights hooked up, I discovered that the
right low beam would still not come on.  Furthermore, I found that
when I pulled the rotating switch outward, the fog lights no longer
came on.

I'm not an expert on these or any other cars.  I gave up after I found
a little fuse box under the hood on the driver's side.  All of the
fuses appeared intact, although I must admit that I'd never before
seen fuses that looked like these; I observed that none of the little
metal strips were burnt or missing, and that everything was firmly
seated.

Now it's vehicle inspection time, and I need to resolve this annoying
issue.

I ask you: what's up with this crap?  Does it sound like something
simple, like a bad headlight switch?  Or am I in for wiring hell?

I'd prefer to take the car to a professional rather than do further
damage by attempting a complex electrical repair myself. I'd
appreciate it if an experienced W123 person could tell me what kind of
trouble I've got on my hands.