I haven't ever had an 1800ES, closest is the 145E I am working on now.
Should be pretty similar though.

I don't recognize the term "B+". Most of the alternators I have had were
SEV/Motorola so that might be why. The one in the Yellow Peril is Bosch
and I have an Echlin VR32 regulator on it. It has 2 connections and clear
marking on the lid saying DO NOT GROUND EITHER TERMINAL!! One is marked
Field, has a green wire that goes to the spade terminal on the back of the
Alternator (the brushes) and the other is marked IGN. It's got a red wire
that goes to a smaller screw post terminal on the back of the alternator
(Not the big heavy output terminal). Another wire hooks to this terminal
which disappears into a jacket with the output wire and (I'm pretty sure)
goes to the amp light.

The VR-32 has a jumper on each side inside the box and an adjustment.
I suspect someone either grounded one of the terminals or pushed down
on the regulator relay at the wrong time because one of the jumpers had
burned in two. I replaced it with about 4 strands of fine copper wire
soldered in, and it works OK now. I did have to adjust the adjusting
screw (which controls relay spring tension) to get it to put out 14 volts.
If you have a similar regulator (brand immaterial) you may also have this
problem. If so you will get no charging till you fix it.

Philosophy: Anyone who charges you $600 for working on an old car and
does NOT fix the problem is NOT your friend. You need to find the old guy
who fixes starters and generators in your area and has a bunch of them
lying around his shop among motor-driven testers, meters, etc (NOT computerized)
and get him to help you if you can't get this worked out yourself.
Don't go to somebody who specializes in foreign cars with shiny paint jobs.

The Bible says "Where no oxen are, the stable is clean." In other words, if
there is productive work going on, there will probably be some mess.
--
George Downs, Bartlesville, Oklahoma, Central US