I've got an older, fireplace prefabricated insert, with a heat exchanger or to put it simply, a thin walled 6” pipe in the top of the firebox, with an inlet and outlet in the face of the unit. There is a non functioning fan inside the pipe. The fan is not repairable in my opinion. I’m looking for information on the unit (brand name, manufacturer, era etc.) and ideas on replacing the fan. Is it worth it? Is it possible to find parts? where should I begin? I know absolutely nothing about the manufacturer or model. And there are no markings. It looks to be 60’s or 70’s era and is brass, that’s about all I know so far.