kids = sticky soda residue on metal dome.......

Bless my darling little children.... how can I remove dried (almost like hardened glue) soda residue from a metal dome tweeter?? Evidently, the soda was spilled, unbeknownst to me, and dripped/drizzled through the screen and onto the tweeter, leaving several thick spots of residue. I can't hear anything wrong with the sound, but I would still like to clean it off without causing any damage to the tweeter.

Thanks.

Ben