I am replacing my kitchen faucet but run into some trouble. I am having a hard time removing the center part of the faucet under the sink. I included a couple of pictures. I tried unscrewing it by hand as i did the other two, but it won't budge. The nut seems like is encased in this black plastic thing. I tried prying it off so i can get into the nut but no luck at all. Does anyone have any suggestion on what i should do? Ps. I did not install this.