Are the B&W 700 series sterilized of late?

Elizabeth, that's so nice of you. Civility is good.

Yes, all 700s Serial numbers are consecutive and come in pairs.

I would remove the woofer, to check if there are any bugs, or mice that might have crawled in through the speaker ports. Very common for speakers that are used in a basement system, cause the wife would not let them have a system set up in the living room of the house. Never buy a speaker from a basement audiophile!!!