Do you have the rear suspension's front shock spring too tight? This will cause the sled to teeter-totter. You can tighten the straps to overcome this. But, if the spring is too tight, it should be loosened first. All you need is enough tension on the support ring to hold it in place when fully extended. If you set the spring that way, when you sit on the sled, the shock will compress properly. If the Spring is too tight, the shock will not be able to compress leaving you with a fulcrum to teeter-totter on.