Hi,
yep, pull off the back and expose the main jet.
(Check the flame height while you can see where it is, it should be like a small Bunsen burner, nice blue flame about 12mm high with a bit of noise)
The only wire I had at the time that was fine enough to clean the junk in the hole, was a strand of wire from a metal flywire screen, but you may find, or some one may suggest a better source.
Take care not to twist pipes as you undo the fittings, a second spanner can help holding the mating fitting.
Cheers
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