Out of no where I hop on the quad and it won't back up. I try to go forward and it won't move or stall. So I twisted the screw IN on the lever until it stalled out and started to move. I rode it on the sandbar and at full throttle it just wasn't moving that fast. Possibly slipping? Not sure what kind of oil is in the motor as I got it less than a month ago and it had fresh oil change.