situation - I had my left wiper go gradually and it's left a bit of a mark on the windscreen that will not budge whatever I have tried cleaning it with, re materials or solutions. the 3/4 inch band comes across as a little opaque when in the sun.....
what would you to recommend to get rid of this annoyance.....?
I use Morrison's own brand toothpaste at 50p a tube for a lot of cleaning jobs. I've used it on glass and mirrors but it does need properly washing off
T Cut wont harm a windscreen. Depends though if the marks are reisue or scratching from the metal blade.
If scratching, the time honoured method is to use jewellers rouge, a very fine abrasive.
If you've let a wiper "go gradually", I think that it's most likely damaged the surface slightly..rather than deposited something on the surface that can be removed. If the opaque band is in an arc, then almost certainly the poor wiper edge has etched (dirt) into the surface.