Publisher Rescue
A folder of aging .pub files goes in; a list of what each one is and whether it is worth converting comes out.
Triage your whole folder: what each .pub file is and whether it is worth converting.
Publisher Rescue is free, and stays free. No account, nothing to cancel.
Email support@avyth.com and the person who built Publisher Rescue reads it. If it fails on your file, say what the file looks like — that is usually enough to fix it.