Looks like the original method was to crimp the wire in a ferrule and then use a spot welder to weld the brass tube to the brass strip. Without acess to a spot welder the only method that will work is to use either a brazed joint or silver solder, as a soft soldered joint ( plumbers solder or ant electronics solder) will fatigue loose with time. There you need a hard solder joint for reliable life.
Best is to throw it away ( or scrap for the brass content as well) if you do not have brazing rod and flux, or silver solder rods, either self fluxing ( used for airconditioning) or with a flux coating. There you need a gas torch to provide the heat, as no soldering iron will get that hot, except possibly for the big 300W soldering guns with massive tips.