caravan gas fridge won't go cold?

I have an old caravan, (1970's), with a gas only fridge which won't go cold, the pilot light works fine and burns blue but the fridge won't cool down, it has been standing unused for a long time, I have taken the fridge out of it's recess and turned it upside down which usually cures most fridges but no luck.
Does the fridge need re-gassing and is this possible still ?, any ideas on this problem would be much appreciated.