By the way, I neglected to mention that the ball-and-socket is plastic,
with a metal band in the socket.

Then I'd be careful using my suggestion because the solvent in the
stuff may attack the plastic. I assumed metal parts. There is some
other stuff I use on rubber parts, like the window gaskets in my car
and truck. It's a dry lube made by, I think, Borden. Anyway it's some
type of white looking powder suspended or dissolved in some type of
fast drying liquid or solvent and comes in a spray can. I sprayed the
stuff on the rubber gaskets and now the windows go up and down much
easier. Of course it also may attack the plastic.

"If it's Borden... it's got to be good."

I've also thought of using graphite powder.