I have never used breadboards before. It comes with an aluminium (I think) strip at the underside. Is this strip just to protect the double sided tape at the bottom of the board or does this have a function?
I might sound stupid in saying this, but I never really thought it served any purpose at all, I thought the metal strip was just some kind of screwup, but if it happened more than once it’s probably in there for a reason.
The only idea that springs instantly to mind would be replacing the conductors on the bottom (as they do eventually go bad if you’re rough with them, but I’ve been gentle to my breadboards and I’ve had them for years now). Other than that I’m as clueless as you.