Probably broken glass or china stuck in pump impellor it can accessed from inside the machine :- remove filters etc and bail out all water, look down in sump on left you will see small plastic cover held on with 1 Torx head screw, undo this (noting which hole it is in, there are 2 holes only one screw) remove cover you will see impellor and can remove glass etc look also under impellor. Cheers
Kenjo
May 2012