Not sure if a dry joint is your problem Ant, but it will do no harm to check.
Run yer iron over underside of the board, bad/good places for dry joints are the legs of transistors on heat sinks, transformers, sometimes its possible to see a faint ring of oxidisation around a dry joint but not always,might be a hint of burning if it has been arcing, be carefull you don't short across any tracks though.
Most monitors I have come haven't been difficult to get at the motherboard, this one was a right pig,
Anyway its ok now still havent got it back into the case yet though, been busy doing other stuff