My Apple IIc is what appears to be the first US model: A2S4000 with version 255 ROMs. The upper half of the case is held to the base with six Phillips drive button-head 2 cm screws with a very wide thread, of which I'm missing two. They look like this:
The front four screws going through the keyboard tap straight into plastic sleeeves molded into the case, so there's a danger of destroying the existing threads of I use the wrong screw (which obviously I want to avoid). The rear two screws go through a hole in a plastic tab with a small piece of thin sheet metal, with two similar holes, folded around it, so I am guessing that this would conform with screws with a different pitch.
What are these screws called, or what terms should I use when searching for replacements? What are the dimensions I should be confirming (I'm likely to be ordering these over the Internet) and, if you don't already know what dimensions Apple specified for this screw, how ought I measure them?