you could try giving the blades a wipe over with a drop of vinegar.
i use vinegar for most of my window cleaning and find it gives a brilliant finish.
:-)
wipe your blades with wifes nail varnish remover, when going though car wash put a rear wiper plastic sleeve over them it keeps the wax off them, I do it all the time always have clear screen,
also vinegar in he water when you wash and clean windows to get them really clean