M3 or M4 sized screws of different lengths is probably the best start but yeah there are specific screw types that you may need so maybe scouting around the volcano thread might help. Have you used locktight on the screws? If you haven;t I'd suggest removing the screws and add locktight to them. You shouldn't really lose any after a bit of locktight.
I'd also retitle this thread and call it "replacement screw kits". Then someone might see it and help out.
Cheers