I have a (SS) AM/FM/SW radio which has a similar symptom, the volume no longer goes all the way down. I'd try to shoot some "cleaner" into the pot, but the radio is a real "bear" to open up sufficiently to access the pot
As they say "
No user-serviceable parts inside" (or even somewhat accessible)
My first SWAG for the BFA's problem is that the volume pot has gone partially bad, or perhaps there is a "suspicious" solder connection on the pot's "ground" lug, or on the ground end of it's wire.
Perhaps a quick shot of "cleaner" or WD-40 into the volume pot would fix it
/ed B