I think that if you investigate further, the frame is most likely ZA a zinc die cast alloy, with some aluminum content, you cannot silver solder it, or aluminum for that matter, the melting temp is not much higher than lead tin solder, there are solders that will work, as well as welding materials for it, but can be quite tricky, once the temperature is reached to weld it, a little extra heat will cause it to sag or run, if you trust epoxy,it may be the easiest solution