treadmill when turned on is stuck in incline (goes up and down) position. How do we unlock this so we can go use other functions. We tried unplugging and replugging, but it goes right back to the same incline problem, going back and forth, up and down unless we take the "key" out? Please helps us. This is a fairly new (maybe 3 yrs old) machine, and do not use it often. MAllen4u@gmail.com is my email address. Model Number unknown.