I too tried a number of different knives, electric and serrated and ended up finally snatching a fork off the table. The fork works great but leaves a bit more wax in the extractor. That how ever is no problem as I set the extractor outdoors on it's side with the bottom slightly elevated so the wax and little bit of honey drain toward the front. The bees clean it up real good in a few days and the left over cappings are so dry I can blow them out with a hose.
I look over the great cleaning job I did and store the extractor for next year. No fuss no muss.