Has anyone found a spray cleaner that works on those black curtain/run marks you get on white upvc gutters and on some frames? On all the conserv's i do regularly, i also do the guttering at the same time as it takes just quick brush over, yet these stains remain. They will come off if rubbed with a cloth, but that would take too long as the gutters are a freebie as it were.Tfr apparrently doesn't work, although i've not personally tried it yet. All help appreciated. 8)Syd