Hey ,

Have you tried seeing inside the printer to where the pulley belts are? check if there is anything obstructing them like filament , loose parts or something. If it is clear, it could be the limit switch isn't working. Those actually only cost $2 at a local electonics shop. there is just a requirement of soldering and screwing the switch back in the same way the old one is. If that isn't the problem, it might be your stepper motor is wired incorrectly. This may be from incorrect sequence of steps due to wire mix up. Call flashforge and see if they can respond about that kind of problem. The last possibiliy is that the wires are getting pinched somewhere on the machine. This can commonly happen during shipping and it casues the electrical connection to be disabled on and off depending on how pinched the wire is and whether it makes contact with another conductive surface.