It is an UNC screw, I have bought a set (20 pieces, 12 US $ in total) of 10-24, 3/4" long in stainless steel ones from AliExpress, works fine.

Are you sure? I was sure they’re M5
they look verrrrry close to the imperial surf ones.
But they are a tiny bit fatter

I can look at one tmr at work

Be handy to check mark thx..

i tried some m5 screws and they're a touch too big or thread is not right so i stopped. Fcs was about right but not tight which could be from use. Was thinking m4 but like kris says the thread matches the fcs screws so i agree with him they're 10-24. i’ve ordered both m4 and 10-24 unc 24pti. Gonna have to fill and tap one screw hole to repair. My gut is the simmer slot box screws with the heads are m4, the grub screws are 10-24.

thing to also note is the allen key size for the grub screw head is not metric… using a metric key chews out the heads. So an fcs tool which is imperial is needed to adjust grub screws.. fcs tool was the perfect fit for the heads.