[Luxobarge]

As above - perfect description of what you need to do. I would just add that if the panel has been on long enough for the tubes to block, chances are that the pollen filter will be cruddy too, which will restrict the amount of air coming into the cabin from the heater, so personally I'd budget on replacing the filter while you're in there, well worth doing and often forgotten at service time.

It's possible that your car isn't fitted with a pollen filter (mine wasn't) so it's a good idea to fit one, especially if anyone who travels in the car suffers from hay fever etc. However, you'll have to also buy the black plastic surround that it fits into, I got one without too much trouble.