Use tape water, elbow grease and a q tip. Don't use hydrogen peroxide, you might etch the surface of the reed or tone board and ruin the sound of the call. If you are dead set on a solution, use rubbing alcohol.
Current MFG. Rep of chemicals chimming in.
" Never show up as a guest on a hunt with your dog. Never take the best shooting spot. Leave the call in your pocket. Never ask to come back. Keep your mouth shut after the hunt. Always bring gifts. "