New Hippy's who started this thread stated the the fridge is ok on 12 v & 230 v, so there'll be nothing wrong with refridgerant, air locks, out of level etc.
I'm sure it'll be a blocked / dirty jet, burner, or flue.
It's an easy job to tackle, especially if your fridge vents are easily removable ones ie with the little plastic 1/4 turn screws. If they are the older style, with numerous screws around their perimeter and set in mastic it's a little fiddly & messy, but still worth doing.
This is a recurring problem that many have had, I posted this in 2009 as the most likely cause and the remedy :-
''you've got to dismantle the burner assembly, then the remove the jet from it, then throw the jet away and replace with new one. It's possible to clean the jet, very carefully with a fine strand of wire.
Remove bottom fridge vent.
Remove the wind sheild from around the burner assembly, this will be held in position by 1 or 2 small screws, and will require tugging a bit, but it's only thin tin and will take this. Then remove the union nut between the gas inlet pipe and the 'square' section assembly. The gas jet is 'held' in position between the end of the gas pipe and inside the burner. Then disconnect the small cable (gas ignition cable) and the thermocouple line (thin bendy metal pipe). You'll wonder were all the muck comes from during this dismantling !
Give the burner a good banging and poking and cleaning with a pin, you can't damage it.
Then take the top fridge vent off.
Remove upper section(s) of flue, these are usually quite loose and don't need to be gas tight. You'll see / feel a thin steel wire which is hooked over the vertical flue lowest pipe, pull this up. A 'swirl plate' is attached to this, and will certainly be covered in carbon This needs cleaning till it shines. Then get a flue brush or something to clean / push through the remaining length of flue. I always put a sheet of white paper at the bottom of the flue to see how much rust, sh*te, etc falls down.
Then put it all back. I'm convinced that this will cure your problem.''
Hope that sorts it.
regards
Allen