Hello all,  In response to Spence Chase's posting...   Luckily I did
rescue the lamp socket.  It was sort of flat as well but I managed to
salvage it and it has now been working for 10 years or so without any
trouble.

What was not so clear in my first posting is that I do have a modern
candle style 40W bulb in it.  There is just nothing suitable out here
that is 25W and tubular.  The shade itself could unfortunately not be
rescued because the metal stretched out of proportions when it was
flattened.

The lampshade I am looking for is the only type I have ever seen on
these pianos over here and is seems identical to the one on a piano
that a friend of mine brought over from the USA a few years ago.  It
is a nickel plated metal shield and it looks exactly the same as in the
service manuals.  It clamps to the socket with a type of split clamp as
mentioned by Spencer.  Please, if anyone has a spare one lying around,
I would be grateful.

Kind regards,

Bernt Damm
Cape Town