Try Umarex. Saw someone on GTA not long ago that got warranty repair from them for same part on a 48 and they were originally going to just sell him the part.
Is it the pull rod? (part #27 in the diagram). A fairly common failure and the rods used to be available everywhere, now everyone is sold out or out of stock except I found some available on ebay. https://www.ebay.com/itm/234574650007
We ship worldwide - Airgun, Shotgun & Rifle spares, parts and accessories for for Air Arms, BSA, Crosman, Diana, Gamo, Relum, Webley, Weihrauch and more