I have two very productive quince trees, however a large proportion of
the fruit is affected by a "problem". The skin has largish numbers of
tiny black / grey dots and when you cut (hack!) the fruit open the
inside is heavily veined with brown to such an extent that 50%+ of the
fruit mass is brown and because it's veined that makes 100% of the fruit
mass useless.

Does anyone recognise this condition and can anyone put a name to it?
And ideally of course, I'd like to know what I can do to prevent it in
future.

Many thanks

Merl