Odd Problem with external drive permissions. PLEASE HELP!

I have an external USB drive with a TimeMachine backup from another Mac which I don't have anymore. For some reason I can't read the drive. I know this is definitely a permissions problem. Here's the current info:
1- The drive mounts fine and I see it in Finder. The problem is when I click on it to see its contents I get the error message: "The folder VERBATIM can't be opened because you don't have permissions to see its contents".
2- "Get Info" on this volume shows the drive icon with a lock on the lower left corner.
3- Access shows as: "You have custom access"
4- Permissions for all (myself,staff and everyone) are set to custom for some reason.
5- "Ignore Ownership on this volume" is checked.
6- If I try to change the permissions for myself from custom to read/write, it reverts back to custom. Odd.

I'm attaching some screenshots. Any ideas will be much appreciated. I'm in the middle of an urgency here.
Thanks in advance.

 

One more thing

Forgot to mention that I also tried sudo chown and sudo chmod from the Terminal and still no luck.