In order to check the down-force adjustment, place a two-by-four wooden plank on one side of the garage door while the door is fully open. Make sure that the two-by-four is directly under the door opening. Close the garage using the garage door remote. As soon as the door comes in contact with the plank, it should come to a halt momentarily. After the brief stop, the garage door should reverse direction until it returns to the fully open position once again.
If the door does not reverse direction when it comes if contact with the two-by-four, you need to adjust the down-force limit. Climb a ladder placed close to the garage door opener motor assembly. At the rear of the assembly, look for down-force adjuster screws. With a screw driver, slowly rotate the down-force adjuster screws in a counter clockwise direction. Climb down from the ladder and again check the down-force adjustment as you did in the earlier step. Keep making small adjustments to the down-force adjuster screws by rotating them counter clockwise until the door reverses when it comes in contact with the two-by-four.
Now it comes to checking the up-force adjustment. Position yourself inside the garage, facing towards the door. Open the garage door using the garage door remote. The door slowly starts to open. When the garage door has risen halfway, grab at its bottom and apply a downward force. If the garage door is properly adjusted for up-force, it should immediately stop moving as soon as you apply the downward force.
If the up-force limit is not properly adjusted, the opening door will not step when you pull it downwards. If that is the case, you need to adjust up-force adjuster screws by rotating them counter clockwise in small increments. Keep checking the up-force adjustment as you did in the earlier step until the door comes to a complete halt when pulled downwards while it opens.