Razor E3005 Electric Scooter ?

I have a Razor E3005Electric Scooter, and when I go to ride it the drive wheel wont spin, and the chain is not engaging. When I turn the scooter on its side or upside down, the chain is now engaged and the wheel spins at full speed. It seems to me that when pressure or resistance is added to the scooters drive wheel the chain stops engaging even though the motor is still working when the throtle is used. My best guess to the problem is that the sprockets are loose. How should I Tighten them? Also, if this is not my problem what is, and how should I fix it? Thank you