Discontinued does not mean lost, it just means the manufacturer stopped hosting it. There are archive sites that hold scanned manuals going back decades, including service documentation rather than just the thin owner’s booklet. I have used ManualMachine https://manualmachine.com/ a few times for exactly this, they list a huge number of brands including older industrial equipment. Search by the plate number rather than the marketing name, that is what matters on old machines. If the plate is unreadable, photograph the casting numbers, those often narrow it down to a family of models. Also check whether the manual covers your voltage variant, machines from that era were often sold in several configurations.
