My incline has stopped working?

My incline control panel electronically shows that it is stepping up, however the platform does not incline. I see 4 LEDs on the power control board, but one is not lit. My speed control works fine. I checked all the wire connections and found them to be in place. Is my power control board bad, or is it the lift motor? I hear and see the motor try to work, but only turns about 1/4 turn while starting the decline. But beings it is already bottomed out, obviously it won't go any further. If not the power control board, where else can I look or are there any other ideas?