I just acquired this dozer, still learning a lot. When I press the button on the joystick, the display shows the "blade release" icon but pushing the joystick forward does not engage the "magnetic hold" on it, nor is the blade dropping on the ground to follow the grade. The blade just moves down as if the blade release mode wasn't engaged. I checked the fuses and they were good. Anyone can point me where to look next that would be great. I have the service manual but it does not (from what I can) provide steps to diagnose the problem.