Their is really only one good way of removing gum , that is with heat, either low pressure steam machines or hot water pressure washer. The low steam machine also uses a chemical to break down the gum once heated.
In my experiance you cannot always get the stain out (animal fats) from the surface , I think the degree of staining depends on the porosity of the surface being cleaned.
I am not being rude but some of the questions on here seemed to be asked over and over again , have a look at previous posts and you will find a wealth of helpful information there.