YOU WILL NEED:
Lemon
Iron nails
✤ Drive the nails with some force into the lemon.
✤ Visualize the evil eye being pierced.
✤ Keep the lemon for three days, by which time it should begin to rot.
✤ If it does not, repeat the procedure.
Here you have externalized the difficulty, checked that the spell worked and repeated the procedure if not. You could then repeat the diagnostic procedure to ensure that you are clear.