Basically the residue is still on the glass from the price board, which is why you can still see it when the glass fogs up... where abouts are you based? We may have something that will shift it so could either send you a small amount to try, or if you're local we could get some to you and have a look at it for you
Thanks autoperfection i'am based just outside Belfast N. Ireland, if you could send me a sample, cause it is realy starting to bug me now.