I advise Michael Pawelek not to simply obtain a reed that plays G-sharp
for his Melodia.  Organette manufacturers didn't really care about the
pitch of their instruments, and it didn't really matter either since an
organette will always play solo.  The pitch of Michael's Melodia could
well not match up with any known standard.

Reeds for organettes are not a problem, particularly models like the
Melodia which employ standard sized American Organ suction reeds.  Most
organette repairers have large stocks of reeds taken from scrap American
Organs and you will find that the standard brass semi-circular ended
reed body will fit the Melodia.  You will need to provide the next reed
(A-sharp) to get the correct pitch, i.e., find one that is one tone
below the nominal A-sharp.  You would be unwise to buy a reed 'blind'.

German organettes tend to use steel reeds played on pressure, so brass
American Organ reeds cannot be used.  Scrap accordions are a good
source of spare reeds.  Making your own reeds is surprisingly easy.
You just need some thin stock and a lot of patience.

I recommend that Michael buys 'The Organette Book'.  This includes
a section on restoration.

Best wishes to Michael in his restoration,
Nicholas Simons, England.