urq brake system help needed

[Steve Marinello]

Some new twists with the '83 urq...

The brakes started acting like MAYBE the bomb's going
out...rarely/intermittently hard upon braking, but always coming off some
mild acceleration.  Pump test checked out...initially.

Noted that the fluid level was down slightly and topped it off.  It went
down.  Topped it off again...and again, and again ad nauseum until it filled
up for good (pedal pumping in between fills).  Noted some black particulate
dregs floating up after about the third fill.  Overfilled slightly the next
two times and floated the dregs out.  Total volume in was probably 40% of a
can of Castrol LMA, which is what I had on hand.  Brakes had been flushed
and filled at the dealer in August 1999.  Car had seen little usage until
October, at which time it became the everyday car, getting about 70 miles
per day minimum.  Bomb and regulator replaced in May '94(?) before the first
q-club Second Creek run in Denver.

Brakes immediately improved in feel (???).  Everything fine with no
occurences for about three weeks.  But they're back, and more frequent.
And, the brake fluid in the reservoir has taken on a decidedly darker tint.

Contamination from where?  Where's the breech?  Where to look/check?

With an offering to the Audi Gods, I beseach the lists' assistance.

TIA,

Steve