Here is something I stumbled across and thought I'd pass it on.

I recently acquired a 27" Regina disc of one of my favorite music box
tunes, the "Under the Double Eagle" march by Wagner.  It looked great
-- little if any rust, good projections all there, minimal dents, etc.
But when I played it, unlike any other disc I have, it squeaked like
a son-of-a-gun.  I tried several things, including smoothing out the
drive holes on the rim, without much improvement.

I was on the verge of putting it away as unplayable when the "it can't
hurt" notion of waxing it occurred to me as a way of reducing friction.
I used an old standby for metal surface cleaning, Meguiar's Cleaner Wax
for autos, applying a thin coat to the front of the disc and to the rim
on the back, being careful to avoid getting any into projections.  Then
I waited a bit and buffed it with an old T-shirt (what I also use to
apply the wax).

Bingo!  Zero squeaks!  And there's a little side benefit of rust
protection for the front of the disc.

I kept the wax coat thin as I did not want projection holes clogged
with wax.  You will get a few but wait about 24 hours and any wax in
the holes will show up white when the wax dries and you can flip it out
in a moment using a toothpick.  The same with any you might accidentally
get on a projection.

You can get the Meguiar's on Amazon for about $5, or at your local auto
supply.  I expect any good cleaner wax would do the job.

Note that while this works well for a basically sound disc with a
little surface grunge, it likely would not remedy squeaks caused by
dents, corroded surfaces, etc.

Clay Witt