Hi Jerry,  Here is the simplest way to replace the bellows cloth
on your organ.  Pack it carefully and send it to someone who has the
experience to do it for you.  An excellent choice would be Harold
Draper at http://organetterepair.com/ 

The second choice would be to contact Harold and see about buying
the necessary materials and replacing the bellows cloth yourself.
It would probably cost about half of Harold's very reasonable charge
-- the bellows cloth is rather expensive.

But before you do either of these, you might want to see if you can
solve the problem another way.  Often ozone or other airborne chemicals
cause the 'rubber' on the cloth to get hard and crumble.  Sometimes
you can actually restore the cloth.  You'll probably have to remove
the bottom of the case to get at the bellows and the reservoir.

Then get a bottle of Pliobond from the hardware store.  Pliobond is
basically rubber dissolved in a solvent like acetone.  Thin it down
a little and then paint the bellows and reservoir wherever you can see
the cloth fibers.  Then go over the entire bellows and reservoir with
a second coat to seal all the cracks and flaking places.  Make sure
that it is dry before you try to use it or the surfaces will stick
together.

You might also have to replace the valves on the bottoms of the bellows
if they are warped or curled.

Regards,
Craig Smith