Good advice thanks.
I found an O ring in the sump hose.
I checked & flushed the other hoses but there are a couple of rectangular plastic boxes about 8" long just inside the machine. I have no idea what these are but the water passes through them before it reaches the hose on the outside of the machine!
As far as I can tell the pump is performing OK but I guess this can only be checked by the noise it makes
I will see if the problem is solved by removing the O ring & let you know.
Peter
October 2012