Just tried this stuff to weld the aluminium legs on Emily. It is well worth a look as it melts with a normal fine tip torch and is really easy to use. I will be fixing the broken bit off the tiller stock now. Buy on ebay for £14 for 2 meters and really does do what the videos on utube show.
Melts at 350C rather than 600C so as long as get it all hot enough it is easy.
Since found out that this is actually zinc. Creates a very good joint and very strong, however not to be used where constantly wet as will sacrificially corrode to protect the aluminium. If used where constantly wet make sure it is painted.