Thank you for all the responses. Yes, I made sure the gears moved easily during assembly and have tried multiple motors. When I built the LEGO Creator Expert 10244 Fairground Mixer and attached the motor and battery pack everything worked perfectly. Yet the same battery and pack does not work on either the heavy lift helipcopter or the arctic truck. Like the helicopter, when I manually engage the various gears on the arctic truck every facet of the model works perfectly. The crane rotates and goes up and down, the bed of the truck tilts effortlessly. Yet when I try using the motor nothing moves. I am wondering if I am doing something wrong when attaching the actual motor to the device. On both the helicopter and arctic truck, there are two black connector pieces that on either side of the axel. When I remove those connectors and attach the motor to the axel, the motor works perfectly, of course, except for the fact that there is nothing holding it steady and as it turns the axel the entire motor casing also tries rotating. The problem always arises when I reinsert the black connectors into the motor (which I presume are there for stability purposes), only then is the motor incapable of rotating the axel. Please let me know if this is making sense. Thanks