On Wed, 22 May 2019 12:53:51 +0100, Adam Funk
wrote:

When I used it last week, I had occasional problems with it: switching
between "neat blue flame" & "orange flamethrower", occasionally going
out, & leaving some wet-looking stuff on the nozzle. Does this just
mean the tank is almost empty, or is there something wrong with the
handle/nozzle?

Did you have the fuel tank upright all the time you were using it?