I'm not sure what the gasket is from your description, do you mean the cork ring around the frame lip? Not sure how a kick to the package could damage that. Photos?
If you push them gently with your hand, do the cones move freely on both speakers, without rubbing sounds? If they do, the cones are probably okay. Have you played through them yet?
The E-120 is a real PITA to ship well, I've had lots of problems. And if there is a sharp impact, the pole pieces can become misaligned,it freezes the cone and the speaker is trash, can't be reconed. If you're shipping a pair, it can be effective to bolt them to each other, that will protect both cones. Or, bolt a piece of thin scrap plywood over each cone.