u know those sticky magnetic rubber rings you can get in halfords to hold ya tax disk holder.. well.. whoever had my car before me put it in a really stupid place on the screen..
tried once with my nail.. no go, tried putting nail varnish remover around it.. no go, tried picking bits off with a small sharp knife... slow progres..
despite warnings to the contrary ("you'll only make it worse") a hair dryer works really well.. heat it up, and it'll peel off pretty easily, then use nail varnish remover to remove the lil bits of glue left. which was not much in my case apart from where my other attempts had failed.
