The very best thing you can do with your Fletch-Tite and other glues is throw them in the trash and get you some Bohning Fletch Tape. Greatest stuff ever invented. I was sceptical at first, until I tried it. No more waiting for glue to dry! Once you get good at it you can fletch a dozen shafts in 15 to 20 minutes. I have shot arrows under grass and through brush and everything possible and never had a feather torn off, even got them totally soaked with water and they won't come off. This may not help you with your hardened glue, but merely a suggestion that worked for me.
Thanks,
James