My kit did not seem to come with the short screw to affix the earth cable to the heated bed. What are the specifications of this screw? Did everyone else get that screw, I'll dig around but I am fairly certain I don't have it. Also, I vaguely recall seeing in a guide somewhere an image where the area around the earth had the coating scratched off to expose the metal for the earth, however all of the guides now just show affixing the screw, was I imagining that? I assume it is not necessary now.