should be fine, once its mated up with the clutch lever it will be pushed onto the circlip and backward and forward movement shouldn't matter so much.
How much forward and backward movement? Rotation is normal, as long as its not a real loose fit. Is it the original slave or a replacement one? if so, does it look the same as the old one?
How much forward and backward movement? Rotation is normal, as long as its not a real loose fit. Is it the original slave or a replacement one? if so, does it look the same as the old one?