Can anyone let me know where I am the most likely to find genuine new spare parts to fit the Original target pistols and rifles that use the Giss recoiless system?

I would also like to find a supply of these parts that others have had good experience with that they can recommend.

I am told that the seals for these early models were a bit "suspect" and liable to break up after all these years since they were first made - but that some made from more modern materials are now available that should last "forever".

Does anyone know if these new type seals are genuine Diana/Original manufactured, or are they made by a third party suppier?