How can I fix my Glow-worm Fuelsaver 40B MkII?

Over the last few days the pilot light has been going out without warning, and has been very difficult to relight (lots of ignition button pressing). I worked out that the pilot light would extinguish when the central heating and hot water were turned off, as long as one of them was on the pilot light would stay on and would burn strongly.

Today, however, the pilot light is on (very weakly) and even with the central heating and hot water on it does not fire up to the usual full flame meaning that I do not have any hot water or central heating. I read that the pilot jet may need to be cleaned (unblocked), how would I go about this? Is there anything else I could do myself to the Glow-worm to sort this out (cleaning, unblocking etc)?

Thank you very much, I would appreciate any help or suggestions.