Answer: I can't really diagnose the problem without seeing it, but it sounds like pear psylla damage. Here's a publication with photos that might help you identify the problem: http://www.virginiafruit.ento.vt.edu/psylla.html
If the photos don't match the damage on your tree you might want to take a sample of the leaves and the fruit to your local cooperative extension office for help with diagnosis and control tactics.
Best wishes with your tree~!
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