I have the same issue and for ages I've been stumped. I think now it is the coffee holder which is blocked. My machine came with 2. One is for 2 cups and one for 1 cup. The 1 cup one is fine but hasn't been used much and if you hold it up to the light the holes are all clear. The 2 cup one is awful and when held up to the light many of the holes are blocked.
Matthew Roberts
July 2008