Hello Dix,
my first idea was to rebuild the cylinder. But when I opened it I first noticed the demaged surface. Asking Keith (BHM) with some pictures by Mail and a German friend with a real look at it - no chance.
The next call with Keith we both think it would be good to have a look in the slave cylinder. Done. No flakes. So with some luck in this point only the master cylinder must be new.
I‘m affraid without this check after some time the whole system would be flushed and demaged by the flakes.
Greets René
