Remove storm window goo/glue/caulk from aluminum flashing?

I recently removed old storm windows on my home to install new replacement windows but, when the storm frames were pulled, the goo/glue/caulk (I don't know what it is) that sealed them to the flashing was left behind. It almost looks like some-kind of tape sealant that was pre applied to the storms before they were pressed/screwed into place. Goof off isn't working and I assume goo gone will remove the paint from the aluminum flashing. Any ideas what this stuff is and the best way to remove it? I dont want to have to reflash all the windows on the house because of some goop.