New machine and don't remember vault password for a secondary vault

@pj_gpg - If you have the previous Mac's ~/Library/Application Support/1Password 4/Backups folder, this won't be hard at all. A tiny bit time consuming, but not hard or dangerous. And no, you probably weren't using 1Password 4 on the older Mac; that's what that folder has been called - for legacy and consistency reasons - since we transitioned from version 3. In other words, you could have been using a really old copy of 1Password 4 for Mac...but I doubt it. All versions of 1Password for Mac up to and including the current one use that same 1Password 4 folder in Application Support. Here's what you do:

1. Attach the drive that has the copies of the older Mac's 1Password Backups to your new Mac as an external drive.
2. In 1Password on the new Mac, make a current backup by going to 1Password Preferences > Backup and clicking "Backup Now."
3. Still in the Backups tab of Preferences, next click on "Find Backup." A navigation window will open.
4. Navigate to the drive with the copies of the OLD Mac's 1Password backups and locate the most-current one (usually on the bottom, depending on sort order).
5. Select it and click "Add Backup." This will add it to the same location within the current 1Password Library folder, and make it immediately visible in the Preferences > Backup window.
6. Select that newly-imported backup in the Preferences > Backup window and click "Restore." All local vaults from your previous setup should be restored, and unlock-able with your old Master Password (if you used a different Master Password on the new setup, you'll need to use the one you were using before to open this).
7. Go to File > New Vault and create a new vault. Give it a password you can remember, or write it down. :-)
8. Switch to the old vault you don't have the password for, click on the All Items view, and use these instructions to move all the items into the new vault you just created.
9. Go to Preferences > Sync, select the new vault with all the items you need in it and choose Folder Sync. You'll be asked to choose a local folder. Doesn't matter what you choose. Maybe create a new folder on your desktop and choose that. 1Password will write out an OPVault keychain into that folder. Give it a few moments to sync. Shouldn't take long at all unless the vault was truly enormous.
10. Return to Preferences > Backup and examine the list of backups. Choose the one you created in Step 2 of these instructions (i.e. - your current data) and again click "Restore." This will restore the state of your data to immediately before you began this process.
11. In your Mac's Finder, navigate to the OPVault you just created a moment ago and double-click it. This will cause a new vault to be created, requiring the password you just gave that vault earlier. Enter it, and all the data will be imported as a new vault.

From there, you can either leave all that stuff in the new vault, or you can use the Move Items directions from above to move some or all of it to other vaults. You can even remove this vault if you empty it completely. If you're planning to keep the vault, you should probably return to Preferences > Sync and disable the Folder sync, then delete the folder with the OPVault keychain in it. You can set the vault to sync via Dropbox or WLAN from there, as you wish. Your choice. Let us know how this works for you!

@pj_gpg Indeed. Backups are life (quite literally sometimes, in the digital sense). Glad to hear you're all squared away. 🙂