Ive put up with this for nearly 6 months, more fool me and Ive finally checked every component in the chain to discover that the pooping is being produced by the 568.
Before I post it back to the nice people in Huntingdon, has anyone else come across this or knows a solution ?

Incidentally when I told my normally-very-positive Dealer, he simply shook his head and said, "Its a Meridian, you have to expect that kind of thing." Perhaps he wants me to upgrade to a G68.