At the moment I've not had to worry too much about writer's block since I've had quite a clear view of the whole story for Karl for sometime. There were points in the process of writing where some parts did not flow as well as I would have liked. In those cases I put down what I could, and moved on to later sections where I had a clear picture and then returned to the sticky parts later. Basically I write something even if it's not the part of the story I'm working on.
Book 2 of Karl's story follows different timelines, I found it easier to work through one timeline at a time for the first draft.