Chris, one thing about moving the Z-axis via the thumb knob: when the coils are energized, you will notice a lot more resistance. As Ryan said, I also adjust my first layer height by turning that knob. It feels notchy, but that helps me get it exactly where I want it. If I don’t see any filament, I usually raise it up for two clicks. If I see a thin, round line, I lower it by up to two clicks. That’s typically all it takes.