Ultimaker original X-axis not moving - possible electronics problem 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 Ultimaker 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-axis one and it then worked fine. 

Then later the X-axis motor into the extruder connector and is not moving! so I decided to check the step driver and they seems 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! It 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.
I'm not sure I know exactly what is wrong or what steps you've taken so far, but it seems like your extruder motor is broken and you've narrowed the problem down to electronics.

If so, replacing the Arduino, motor, and driver leaves only the Ultimaker PCB as the source of the problem. I would suggest ordering another - but not until you've contacted Ultimaker with the problem you're outlining here.