I'm sorry to say that the damage to the tree is much worse than you see in the pictures. Several branches have died down to the trunk. The trunk itself seems to be of a variety that is resistant to fireblight, and one of the four grafts also seems resistant, but the rest are done for, I'm afraid. With 3 of the 4 varieties dead, I won't have any cross-pollination for the last, resistant variety, unless I plant a new pear of some sort--which I do not really have room for.
I first noticed the fireblight last year, and had removed areas I thought affected, being careful to use clippers dipped in bleach for each cut. However, the poor tree continued to worsen despite my efforts.
Given the state of this poor tree, and my past failure to rescue it, and the lack of a pollenizer for it, I've decided to give up on it and replace it with something else which will hopefully thrive.
Thank you for confirming the diagnosis.