Size of small screws holding motor shells?

we need to replace some of those small black motor screws. Can anyone tell us the official industry standard size of them? We can take the measurements, but thought if someone had the size and tpi (threads per inch), that would save us the hassle.
thanks in advance.

after a bit of research, I am thinking they are M2 x .4 screws in two different lengths. I will buy some and share the success or failure of our efforts.