On Mon, 4 May 2020 12:21:05 -0700 (PDT), wrote:

clean the contacts and buttons. It seemed each time the cleaning effort worked for less than the previous time.

Yes, that's the way it works. Every time you clean them, you remove
some more of the conductive coating.

They sell small conductive rubber pads intended to be glued onto the
existing pads. I have never tried them, though. Using metal might be
hard on the contacts.