I hate to admit it, but I was once a retail stockbrocker. We got calls about old stock certificates regularly.
If you contact a Merrill Lynch-type brokerage (what used to be called a full-service brokerage, now more like over-priced-for-the same-or-less-service-brokerage), they usually have a defunct stock research service.
In the old days (what my kids call anytime before they were born), it didn't cost anything. Just ask any retail broker, who will put the request in, hoping to get your account. Believe me, they like to talk to people who don't hang up on them.
Good luck.