Slabbed NGC Gold Eagle.

For an ngc slab they would have either needed to slide that entire white part out to swap the coin or bent the plastic face enough to gain access to the coin. Since the slab is hard plastic its pretty face to run out bending so any slits would have to be big enough to remove the white part. Basically the bottom edge of the slab would have to be missing.

I agree its highly unlikely they could have done so, however it doesn't sound like something that would be hard to find a replacement. Send it back and get one without a damaged slab. That damage would make it much harder to sell in the future if you wanted/needed too.

At a coin show a dealer I know well showed me a slab that he had opened and changed the coin inside. He made it obvious by placing a Dime in a Cent slab. How he did it, don't know but if he could do it, possibly many others have done so. There are so many slabs out there and no one really knows which are what. However, if yours has thouse marks, I'd suspect opening was a failure. Maybe.

Yea I agree with the other guys here...I dont think someone tried to tamper with it,, more my guess is its been handled rough or nicked around ... and heres why

I have a slab I bought recently of a coin,,, it fell off my desk, banged off the edge, hit my hard carpet cover for my chair. I picked it up, to my disappointment, the edges on one side got nicked really bad, in fact one side looks like a sharp object was used to separate the mold... so bottom line, I think the edges are very "soft" and theres a good chance perhaps it was dinged or dropped and that accounts for what looks like tampering.

hope that helps and congrats on getting a graded gold eagle, I like those coins.