Yes, the wheels turn when the model is lifted.

Yes, I do hear the motor engaging.

There is no signal coming from the wheel side (red side) of the infra red receiver because when we exchange the plug only one side is working (in this case the blue side is working and the red side is not working

The controller is faulty! The left side (red marking control stick) for moving forward and reverse is not working. The blue control stick for turning the 40T black gear is working.

I have contacted Lego Customer Service. They will send me a new receiver.

I would like to thank you all for your help.

Knight, the two diffs are well placed because the vehicle was working perfectly well.

I am sure now that the problems is coming either from the remote control or the Receiver.

Count, I didn't contact Lego custmer service yet. Would you please provide me with the necessary information to be able to contact them. Thank you.

@samar: it looks to me like you've got the user names and the user ranks confused. I think you mean to reply to Gekke Ted and allanp, respectively. The names of the users are in the top left corner of their posts, above the avatar photo, if there is one. ranks are below the avatar photo, and always have a colored star next to them.

I've just purchased this set and had the same problem, looks like the red channel on the rc controller is faulty. I've just emailed lego and await their response.