First off, I'll be honest I despise Eastman as a brand. I hear a lot of people say they have good experiences, but our only encounters have been pieces of junk...

That being said, I agree with the others, if they're silver plated it's probably tarnish. Even nickel silver does it. What you could do is teach the kids to use the area between their thumb and forefinger to wipe that area, and then their finger inside the receiver when they put it together. Make sure they swab it when they take it apart.