This was in another thread recently, I don't have the link handy...
I remember having a heck of a time finding a screw to fit that thred. Reason: It's a metric thread. If you live in the US, you might not have the screw lying around. I happened to find one in my garage after quite a long search.
My feeling for matching screws is: Go to the hardware store with the thing *in hand* that you need to match and start going through their bins.
For some reason, the name "M4" sticks in my mind. Does anyone know if it's an M4 screw?