SOUNDS LIKE THE DIAPHRAM HAS GONE ON IT...
YA SHOULD B ABLE TO PICK UP THE PART IN A PLUMBING SHOP.. THINK ALL YA DO IS TAKE OFF 6 BOLTS AND REPLACE THE DIAPHRAM...
I'M NOT A PLUMBER... JUST HAVE A BRITTONY 11 A AND HAD THE SAME PROB MANY TIMES!
TONY O CONNOR, November 2007