'86 5ktq brakes

[mjs <info4mjs@snet.net>]

hi,

i've been taking my winter car out recently and have noticed the 
following.

my 86 5ktq's brake system is acting up.  first of all, it FAILS the bomb 
test but i'm trying to determine if anything else is bad.  when the car 
is cool, the brake system works fine except for the fact that the power 
assist dwindles after turning the car off.  when the car gets hot, 
typically after baking in the sun all day, the amount of brake pedal play 
seems to increase before any braking action commences.  after moving 
through this "dead zone" the brakes work, except that the rear brakes 
begin to drag.  the more time that goes by, the more the rear brakes seem 
to drag (with no input from the driver).

i've run the system with the ABS on and off and have had similar results. 
i know that i need the pressure accumulator, but could anything else be 
bad, too?

thanks in advance for any input.

mike