Machine suddenly started making an unpleasant noise. Brush removed and cleaned, but no improvement. I removed the brush 'head' (as you would to fit the hose), and switched it on and the noise had gone, so the problem must be in the head unit. I've removed 6 screws (4 cunningly hidden under the rubber wiper blade) but still can't get inside. I've tried unsuccessfully to prise out the front rollers to see if there are screws there.
Any suggestions please?
Ian