I'm writing this Question here hoping someone will be able to help me with the fixing process that I'm currently involved in! Last week during a printing session my Ultimarker original unexpectedly stop working, the problem was on the extruder step motor which push the filament from the back and literally is not moving anymore! the first thing I have done was to check if the motor was burn or something similar. so I swap the extruder motor with the x axes one and work fine! then again the x-axes motor into the extruder connector and is not movin! so I decided to check the step driver and they sims to work all well. so the problem must be on the Arduino or on the motherboard! I bought new step driver a new step motor and new Arduino + motherboard, connected all up and nothing, still not working for the same reason! Is just the extruder motor that won't work anymore! Do you guys have some idea or tips to find out what the problem can be or how can be fixed in alternative ways? Your help will be much appreciated and looking forward for some answers thanks a lot Riccardo