I haven't yet. Is it just blowing off the fins of the heat sink, or is it more involved than that?
Yes blowing of the fins of the cooler and cleaning the fan blades is what I do on regular intervals. I usually remove the fan, if possible, and use compressed air to blow out the fins. If the fan is not easily removable don't let it spin around, hold it with a finger while blowing, since it can damage the bearing.