Halls Cycle used to stock *alot* of the legacy gasgas parts and probably still has a few parts kicking around. I see on their website that they are also a rieju dealer - so *many* of those parts are the same too....
https://www.halls-cycles.com/
Just a quick check so that both "gasgas parts guy" and "az moto center" are rieju dealers too - so they have access to that parts supply chain as well...
jeff