Originally Posted by: JohnGCOn opening one of the 2020 packets I found the strings had a few black marks on them.

You might be able to return them to the store or vendor. If not then use some steel wool to see if you can remove the corrosion as much as possible. That black is nickel oxide, essentially nickel rust. Then put them on & use them until they break! I've done this quite a few times.

Hope that helps!