Does your truck look anything like this? I have the attached, its 1/8 scale also sold under the name tornado, but not smartech name, I bought it last fall while in China and have not seen anything else like it yet. I did find this web site in the UK that sells the truck and parts
link is
www.supermonkey.co.uk
Another site I use while in Asia is realstar21.com there is some information there also.
It sounds like a clutch problem or something is loose on the drive train. You really need to go over everything when working with those off-brand products, something is usually loose out of the box,
Kent