Fuhrman Glass had the correct id.
A Big Thank You. It is Gerald Larcomb & Sally Wicht. I found a picture of a 1970 bowl attributed to them with the same signature. Once I had the correct name, it was almost possible to read the signature.
They had an exhibit at the Indianapolis Museum of Art in 1980. I also found an article about a 1983 show of Ohio Artists in which they won an award (Mindscape Gallery, Evanston, IL) in the April 10, 1983 Toledo Blade. So they were working until at least the start of 1983.