my mercedes windsscreen wiper is struggling to go across the screen. It has most problems in the middle where it does the horizontal bit. It seems to get worse after it rains and does improve with use.

Julie, January 2008

If your wiper blades are more than a year old, it may be that the rubber has hardened or corroded and is not sitting flush with the screen.

Examine both front wiper blades to see if any pieces of rubber are loose, hanging off or missing. If they are, then replace all the blades at the same time. Also, try and compare the wiper arm position to another one on the same model, just in case it's been bent out of shape by a vandal. They are incredbly tough, so any deformation may be quite subtle. Again, if it is the arm, it's quick and easy to replace as it it should be held in place by a bolt and then you only have to lift it off the splines and replace it in the same position.

Brian, March 2008