Thanks @sdayman, that worked. Name = _amazonses, Value = long string with no quotes.
My real problem though, was that SES had changed the Value. We had moved the domain to a new host and registrar; AWS could no longer find the required TXT record, and they began a revocation process. If you get an email from SES about your verification being revoked, don’t just copy the TXT record from your old registrar- instead go to SES and get the value from there, because they might have changed it.