Just thought I'd mention that whittierte on the big auction site is an excellent choice for your slotted bridge screw needs at reasonable prices. Bought them in the past and they are top quality.
I've gotten some too, just like stock.
I've also bought screws from this man. Nice to deal with.
Mike
I have a bunch of his screws as spares too. Well done. Occasionally someone has posted the need for dog springs and he made a bunch of those recently too. I have never broken a dog spring but I have replaced a couple for folks that have.
Dwight