DEX210 issues with diff ?

[Rake]

Hi this is our first RC car.

I have not set it up as it came second hand but hardly used so was set up by previous owner.

The problem is that when in contact with the floor I can hear the mototr going well but the car hardly moves.

I feel its a diff issue but would value some experienced direction here.

If I lift it and run it then the wheels spin ok with the motor but not if its on the floor.

Any advise greafully received as this was for my sons borthday 2 weeks ago and he has not been able to use it yet.

Thanks

Ron.