mounting screws

Hello everyone, I just bought a Vintage Bass humbucker that I am going to install in another guitar. The problem is I bought it used and it only came with 1 mounting screw— you know, the 2 screws that have springs on them and attach them to the pickguard or body and adjust the pickup height...

Buying and selling quite a bit, I always like to change out any screws that look worn or corroded but have a devil of a time finding the right sized screws...Epiphones , same way. They seem to use smaller screws for the neck and bridge humbucker pickup mounting rings, for example, on imports...