How to fix erratic Miele washing machine spinning fault?

My Meile W460 still has wet washing in the drum from time to time. There does not seem to be a set pattern.
Meile suggested running the machine empty through a 60 cotton cycle to re 'balance the drum', did this a couple of times but problem persists although on some washes it is fine. There is no obvious pattern, I have checked filter, all drain pipes & repaced brushes in motor but still the same.
Any suggestions gratefully received.