Miriam, I don't know if you can buy them or not. When my son worked on SMs, if ever there was a spare screw because some new part was installed, he saved the screws. put them in groups in empty prescription bottles! I'm sure he's got hundreds of them somewhere, but I don't know where and I don't think he does, either! Those screws just don't want to be found! LOL
Jeanette