Checking existence of groove on the metal parts by CVS3-RA.
It can detect existence of groove on the metal parts utilizing contour detection feature. It can also check shape of the parts by detecting contour of the objects.

Checking existence of the washer beneath the screw by CVS2-RA.
It can detect color and shape so can check existence of the washer. It's all in one vision sensor so you don't have to worry about space.

Checking side of the metal disk by MVS-PM-R.
It can detect small difference like small marks on the up side and can reject wrong side has no mark.
"stain" function will work fine even if the contrast is low.