fitting new brushes to a kenwood KM250?

Tonight I wanted to use the liquidiser on my KM250 I plugged it in, tested it by rotating the speed controller as always, it ran for about 1/4 second I must have turned it off at about the same time it failed because I did not notice anything unusual. It does literally nothing when I turn it on now, the fuse in the plug looked a little discoloured so I replaced it, no change. What might this be worn brushes. I have used this machine quite a lot in the past but not much in the last few years. Never in a profesional kitchen, only at home.
Thanks in anticipation. Peter Subsequently I turned the high speed output shaft and it worked again, so it must be brushes - how to change these is the question.