Thanks to all of your for your insights. There are a lot of good ideas here for people to talk to and methods to consider. I appreciate this very much.

Yes, we do think it's wrought iron rather than cast iron.

It's good to know that re-melting the clapper might change its properties.

By the way, the bell is so big that two six-foot men could kneel inside it and detach the clapper. It doesn't look that big from the ground, so that was an impressive surprise.