Coincidence, this!  In the Usenet group rec.music.makers.piano lately,
pananima@aol.com wrote:

> A friend asked me to ask you all if anyone has had a similar experience.
> Her technician sprayed a product she thought was called "Tarnex" on the
> wound strings of her Chickering grand, less than 2 years old.  The end
> result was that these strings went dead.  Has this happened to anyone
> else, and what recourse did you have?

I replied --

There was a man called "the Professor" in North London about seven years
ago who used to promise to make stuck upright action's mobile again.  All
he'd do was open the lid, get out a huge pump-action oil-can, gob gear oil
over the centres, snap the lid shut, charge 15 pounds ($23) and make his
getaway.

The amazing thing was that some of these pianos worked for about a week
afterwards, even if not too hot on repetition -- very much like selling
worn-out cars with nylon stockings in the sump.

Dan Wilson