My impression would be that the screw shown in the photo is definitely not an original. Photos of the original can be found on the Soundfountain website, or simply by Googling "SP10 Mk2 platter screws". The screw shown would probably require a washer as it is longer than original and might bottom out in the threaded hole before it achieves its purpose of pulling the platter down against the drive shaft/spindle assembly, without the benefit of a washer. (I don't know that for sure, but it does seem possible.)

