Duncan, I don't believe that there is anything that will take out the glue without harming the carpet. I suggest that you call the place where you got the carpet or the place in your area that seems to know the most about carpet cleanin g and repairs. Hopefully, they can work in a piece of the extra carpet you got when it was originally laid. If not, they should be able to find a piece from a closet or something that's less conspicuous to use for replacing the small section.