'87 TQ Brake probs?

[Michael Spiers <mikes@specnet.com>]

About a week ago, while sitting in traffic I had the hydraulic light come on in
the TQ, then a weird brake pedal vibration.  I hadn't seen this light since,
and I've been too busy to bleed the hydraulic fluid in the thing, although this
is on the list.  Well, on the way home last night, Jerkoff in an Escort wagon
decided to pull out right in front of me, requiring me to get from 50MPH to
5MPH in about three feet or those four rings would've given him a tatoo he
wouldn't soon forget.  I jammed on the brakes hard as I could, ABS kicked in,
car got stopped in a BIG hurry (all the papers I had from work are now
scattered all over the car, man was I not happy with that guy.)  But then the
hydraulic light came on, and stayed on for the rest of the trip home.  Is this
an indication that using the brakes that hard used up the boost that was in the
accumulator, and the accumulator never properly built up the pressure again?
 The car never had any problems stopping, but the light did stay on the whole
way.  Pedal never acted funny either.  I'm fairly sure the accumulator is the
source of my problems, but I'd like to know what the problem is exactly before
I go replacing the dumb thing.  My (her, whatever) '84 5kS has been displaying
these EXACT symptoms for the past four years and 75,000 miles, so that thing
may be due for a accumulator as well (Brakes?  We don't need no stinking
brakes!)  Anyone who can tell me EXACTLY what that accumulator is for?  I'd
sure appreciate some insight!  I know I'm losing pressure (at least I think
that's what I've gleened from some responses I got last week) but I just don't
know why/how.  Thanks much for any info!

-Mike
87 5000CS TQ