I can't adjust the weight on the machne. It will not recalibrate. I manually turned the screw to lower the weight to about 100 lbs, then try to recalibrate and it goes to 340 lbs and stops. The weight shows 10 lbs when it is maxed out. Is the motor broken because it will not turn the screw in the other direction to lower the weight? Do I have to replace the system console?