NordicTrack treadmill Summit 4500X incline problem?

Hi,
I have a nordictrack treadmill that will not incline. If I connect the incline motor directly to 120VAC, I can make it ramp up/down. However, when plugged into the power supply board, it does not respond even though the incline percentage is being changed at the console. I have replaced both the motor controller and the power supply boards. Any other suggestions? The treadmill works fine, except for the incline. I all ready recalibrated the incline but no luck.

Thanks