I opened my blue 1971 Ike 40 years after I bought it. I thought, then, that it would be worth more than it is now. Oh well!
I thought I knew the answer until I bought a 1970 mint set because it was cheaper to get the 1970-D JFK than buying it separately.
Its something with a little studying and practice you can easily do. Its not something you can see with the naked eye so owning a good loupe is important. Your best resource is www.ikegroup.info. You will find a lot of good info at this site. Lots of pics and tips. Hope this helps. Joe
Personally, I'd take them out. The OGP for things from the 70s/80s seem to cause much of the environmental damage on coins that we see today (milk spotting, silver-oxide).
It does help, thx. I actually book marked the ikegroup, very good site for Eisenhowers. Thanks again.