When it rains and the wipers are used there appears to remain a film of something, wax, road grime, or So far the following have failed. Double glazing foam spray cleaner. Cellulose thinners. Meths. Turps. Washing up liquid. A right good cussing. The wiper blades have also been cleaned by the same chemicals and the windscreen washer bottle flushed and washed out 3 times just in case it was in there. Anyone experienced the same or know how to resolve the issue.