Spare screws to fit 7520/Caiman dac case?

I've opened up the Dac again to look at swapping out one of the Murata regs for a Dexa non switching type.
Hopefully this will get rid of the high pitched background "whistle" I'm getting....

As I've had the Dac open more times than a (insert lewd comment here..:)), some of the threads on the little black case screws have become cheesed and dont grip anymore.
Can anyone point to a link somewhere for 4 screws that could clamp the dac up nice and tight again?

thanks.
Gaz.

Big thanks to Stan B who helped me out. :)