60 or 80 grit sandpaper will get the job done; sand in one direction, with the striker call across the grain for maximum friction.
Call will need reconditioned regularly in the field as your season progresses. Good luck!
"So much of this business of hunting turkeys, you stupid it up right at the last.
You do everything right for an hour and a half, and then you sit down here
and there's nothing you can do about it, you made a mistake."
Tom Kelly, [i]Turkey Tales