I've aquired, second hand, a hefty electric strimmer/brushcutter. It's a
GMESS, it says on the casing. It originally came from Screwfix, I think.
It's supposed to have an interchangeable head, either a strimmer head (which
really does make short work of grass) or a four pointed blade for more
troublesome undergrowth. But I can't get the strimmer head off to put the
blade on. The instruction manual is less than helpful, being just a
succession of obscure drawings.

Has anyone got any experience of this model who can help?