I rarely suffer from writer's block. Or, rather, I don't experience it as a paralyzing obstacle to my work. If for some reason the next step in a story isn't clear or I'm having trouble getting it out, the difficulty is usually a sign that the next scene is flawed in some fundamental way. Usually, I'll find that the scene (or some part of it) isn't actually necessary and I'll just skip it and move on. Sometimes, however, the problem can lie in the story arc itself, and I'll have to go back and revisit what I've already written. In any case, I never force myself through a scene. If the next step doesn't feel right, then it probably isn't.