It does appear the heater is blown Jeff , I'm not totally familiar with this Empire model ,as a general rule of thumb Empire boilers usually have a stud that hold the boiler in place , does this one ? I don't know the diameter of the boiler but if it doesn't have a boiler ho!d down stud & if the boiler is 2.5" in diameter And approx 6" long a Jensen belly heater may work for you. Now re:excess solder , I would probably heat it up and remove the s/v bushing and clean up the orafice (empty the rattling particles out of the boiler) & re solder the bushing back on. If you can't find a heater...a immersion rod heater could always be installed , I don't believe this is a rare plant and thus would get you up and running , might as well take it all apart strip the base and paint it a nice Empire red .
Good luck.