I just put together a Ultimaker Original I bought at MakerFaire SF Bay Area two or three years ago. I'm getting this problem. I bought a new arduino, swapped it out, after tracing the connections and verifying continuity and switch operation, and had the same effect. If this is a known issue, could we get some resolution? What do I do next? I worked around it for now, and I'm able to make prints, but I have fear of damaging the machine if something goes wrong.