Spent 4 hours trying to find who made the old carousel in my dead mall, and the answer was in a library basement the entire time | Dead Malls - Discusd
That library basement part gets me because those old records hardly ever get put online. If you found blueprints or a maker's plate down there, there are probably photos and papers about other rides in the same box. Might be worth asking the librarian what else is in that collection, since stuff like that usually gets tossed once a mall is set to be torn down.