And there's "give it a go" for a difficult task.

But "burl?" What's going on down there at the top of the world? Blood rushing to your head?

Later Ah-HA! Tried burl in OED and it gave reference to birl and birl means a spin, a twist, a whirl, a try, an attempt esp in writing!
Another entry gave it as "a knot" so that ties in with a dificult task.

Trumpets!