My cd/dvd player rattles when it plays a disk?

My cd/dvd player rattles when it plays a disk.
It's a mechanical/mechanism rattle not electronic.
I have taken it apart (as far as an amateur can safely do) and pushed and prodded and tightened and slackenend and tightened visible screw heads but it still continues to ratttle when it plays a disk. Placing it on rubber or sponge rubber blocks I find at least stops the surface it's resting on from acting a sounding board for the player's rattle! But how to remove the rattle in the first place????? Model Matsui DV228