If you know what kind of screw it is (check the matching one, you can order one from any number of places.
You can also fill the hole with a styrene plug, add some MEK or styrene cement, which will soften then solidify it, and then drill and tap for a new hole.
Connecticut Valley Railroad -- A Branch of the New York, New Haven, And Hartford
"We don't stop playing because we grow old. We grow old because we stop playing." --George Bernard Shaw