Some advice sought about how to best repair a Cub radiator finned-tube leak. The leak is located on the lower right portion of the radiator tube bank...where a tube passes through the lower copper sheet metal head/panel. Fluid slowly seeping and pooling on the top of the axle casting...and is only noticeable after parking. I tried to solder the leak with the radiator mounted to the tractor but leaking persists. I believe my soldering process was wrong or, with the radiator on the tractor, I could not get sufficient heat on the parts. I am prepared to dismount the radiator this time...could someone share the correct soldering process with me (type of solder, amount of heat, flux, etc)?